週末了，覺得我還有很多作業沒有寫，針對目前大家對OOM的型別不太熟悉，那麼我們來總結一下各種OOM出現的情況以及解決方法。
我們把各種OOM的情況列出來，然後逐一進行程式碼編寫復現和提供解決方法。
1. 堆溢位-java.lang.OutOfMemoryError: Java heap space。
2. 棧溢位-java.lang.OutOfMemorryError。
3. 棧溢位-java.lang.StackOverFlowError。
4. 元資訊溢位-java.lang.OutOfMemoryError: Metaspace。
5. 直接記憶體溢位-java.lang.OutOfMemoryError: Direct buffer memory。
6. GC超限-java.lang.OutOfMemoryError: GC overhead limit exceeded。
第一種，堆溢位異常，相信大家很常見。即堆內物件不能進行回收了，堆記憶體持續增大，這樣達到了堆記憶體的最大值，資料滿了，所以就出來了。我們直接放溢位的程式碼樣例。我們需要設定好idea的VM Options: -Xmx100m，這樣我們設定為最大堆記憶體，這樣執行起來就很快就出來錯誤了。
package oom; import java.util.ArrayList; import java.util.List; import java.util.concurrent.TimeUnit; /** * @author huangqingshi * @Date 2020-07-18 */ public class HeapOOM { static class OOMObject { } public static void main(String[] args) throws InterruptedException { List<OOMObject> list = new ArrayList<>(); while(true) { // TimeUnit.MILLISECONDS.sleep(1); list.add(new OOMObject()); } } }
執行的異常如下，程式碼直接就出來我們看到的異常了。
/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/bin/java -Xmx100m -Dfile.encoding=UTF-8 -classpath /Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/packager.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/tools.jar:/Users/huangqingshi/Downloads/flink-project/target/classes:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-java/1.7.2/flink-java-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-core/1.7.2/flink-core-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-annotations/1.7.2/flink-annotations-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-metrics-core/1.7.2/flink-metrics-core-1.7.2.jar:/Users/huangqingshi/.m2/repository/com/esotericsoftware/kryo/kryo/2.24.0/kryo-2.24.0.jar:/Users/huangqingshi/.m2/repository/com/esotericsoftware/minlog/minlog/1.2/minlog-1.2.jar:/Users/huangqingshi/.m2/repository/org/objenesis/objenesis/2.1/objenesis-2.1.jar:/Users/huangqingshi/.m2/repository/commons-collections/commons-collections/3.2.2/commons-collections-3.2.2.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-compress/1.18/commons-compress-1.18.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-asm/5.0.4-5.0/flink-shaded-asm-5.0.4-5.0.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-lang3/3.3.2/commons-lang3-3.3.2.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-math3/3.5/commons-math3-3.5.jar:/Users/huangqingshi/.m2/repository/org/slf4j/slf4j-api/1.7.15/slf4j-api-1.7.15.jar:/Users/huangqingshi/.m2/repository/com/google/code/findbugs/jsr305/1.3.9/jsr305-1.3.9.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/force-shading/1.7.2/force-shading-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-streaming-java_2.11/1.7.2/flink-streaming-java_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-runtime_2.11/1.7.2/flink-runtime_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-queryable-state-client-java_2.11/1.7.2/flink-queryable-state-client-java_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-hadoop-fs/1.7.2/flink-hadoop-fs-1.7.2.jar:/Users/huangqingshi/.m2/repository/commons-io/commons-io/2.4/commons-io-2.4.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-netty/4.1.24.Final-5.0/flink-shaded-netty-4.1.24.Final-5.0.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-jackson/2.7.9-5.0/flink-shaded-jackson-2.7.9-5.0.jar:/Users/huangqingshi/.m2/repository/commons-cli/commons-cli/1.3.1/commons-cli-1.3.1.jar:/Users/huangqingshi/.m2/repository/org/javassist/javassist/3.19.0-GA/javassist-3.19.0-GA.jar:/Users/huangqingshi/.m2/repository/org/scala-lang/scala-library/2.11.12/scala-library-2.11.12.jar:/Users/huangqingshi/.m2/repository/com/type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oom.HeapOOM Exception in thread "main" java.lang.OutOfMemoryError: Java heap space at java.util.Arrays.copyOf(Arrays.java:3210) at java.util.Arrays.copyOf(Arrays.java:3181) at java.util.ArrayList.grow(ArrayList.java:261) at java.util.ArrayList.ensureExplicitCapacity(ArrayList.java:235) at java.util.ArrayList.ensureCapacityInternal(ArrayList.java:227) at java.util.ArrayList.add(ArrayList.java:458) at oom.HeapOOM.main(HeapOOM.java:21) Process finished with exit code 1
細心的同學可以發現我在裡邊設定了一個休眠，目的是我們看一下堆記憶體的結構和資料圖。我們將休眠程式碼開啟，然後開啟JDK自帶的jconsole命令，連線上之後我們看一下概覽圖，通過下圖我們發現堆記憶體持續不斷的增長。
我們開啟記憶體介面，看一下記憶體，然後點一下GC按鈕，這個時候會有一些類進行回收，但是還是會繼續增長，看一下下面的圖。
點開資訊標籤看一下。經過幾次GC回收之後，類的資料量還是變化不大，說明沒有進行回收。
以上這種情況的解決方法就是找到問題點，分析哪個地方是否儲存了大量類沒有被回收的情況，通過JMAP命令將線上的堆記憶體匯出來後進行分析。
第二種情況，我們看一下棧溢位的情況，“上菜”，下面的程式碼就是無限的建立執行緒，直到沒法再建立執行緒。
package oom; import java.util.concurrent.TimeUnit; /** * @author huangqingshi * @Date 2020-07-18 */ public class StackOOM { public static void infiniteRun() { while(true) { Thread thread = new Thread(() -> { while (true) { try { TimeUnit.HOURS.sleep(1); } catch (InterruptedException e) { e.printStackTrace(); } } }); thread.start(); } } public static void main(String[] args) { infiniteRun(); } }
丟擲來的異常如下，如果真的需要建立執行緒，我們需要調整幀棧的大小-Xss512k，預設幀棧大小為1M，如果設定小了，可以建立更多執行緒。
/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/bin/java -Xss512k -Dfile.encoding=UTF-8 -classpath /Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/packager.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/tools.jar:/Users/huangqingshi/Downloads/flink-project/target/classes:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-java/1.7.2/flink-java-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-core/1.7.2/flink-core-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-annotations/1.7.2/flink-annotations-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-metrics-core/1.7.2/flink-metrics-core-1.7.2.jar:/Users/huangqingshi/.m2/repository/com/esotericsoftware/kryo/kryo/2.24.0/kryo-2.24.0.jar:/Users/huangqingshi/.m2/repository/com/esotericsoftware/minlog/minlog/1.2/minlog-1.2.jar:/Users/huangqingshi/.m2/repository/org/objenesis/objenesis/2.1/objenesis-2.1.jar:/Users/huangqingshi/.m2/repository/commons-collections/commons-collections/3.2.2/commons-collections-3.2.2.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-compress/1.18/commons-compress-1.18.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-asm/5.0.4-5.0/flink-shaded-asm-5.0.4-5.0.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-lang3/3.3.2/commons-lang3-3.3.2.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-math3/3.5/commons-math3-3.5.jar:/Users/huangqingshi/.m2/repository/org/slf4j/slf4j-api/1.7.15/slf4j-api-1.7.15.jar:/Users/huangqingshi/.m2/repository/com/google/code/findbugs/jsr305/1.3.9/jsr305-1.3.9.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/force-shading/1.7.2/force-shading-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-streaming-java_2.11/1.7.2/flink-streaming-java_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-runtime_2.11/1.7.2/flink-runtime_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-queryable-state-client-java_2.11/1.7.2/flink-queryable-state-client-java_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-hadoop-fs/1.7.2/flink-hadoop-fs-1.7.2.jar:/Users/huangqingshi/.m2/repository/commons-io/commons-io/2.4/commons-io-2.4.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-netty/4.1.24.Final-5.0/flink-shaded-netty-4.1.24.Final-5.0.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-jackson/2.7.9-5.0/flink-shaded-jackson-2.7.9-5.0.jar:/Users/huangqingshi/.m2/repository/commons-cli/commons-cli/1.3.1/commons-cli-1.3.1.jar:/Users/huangqingshi/.m2/repository/org/javassist/javassist/3.19.0-GA/javassist-3.19.0-GA.jar:/Users/huangqingshi/.m2/repository/org/scala-lang/scala-library/2.11.12/scala-library-2.11.12.jar:/Users/huangqingshi/.m2/repository/com/type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oom.StackOOM Exception in thread "main" java.lang.OutOfMemoryError: unable to create new native thread at java.lang.Thread.start0(Native Method) at java.lang.Thread.start(Thread.java:717) at oom.StackOOM.infiniteRun(StackOOM.java:24) at oom.StackOOM.main(StackOOM.java:29) Process finished with exit code 130 (interrupted by signal 2: SIGINT)
以上這種情況是幀棧不夠用了，如果出現了這種情況，我們需要了解什麼地方建立了很多執行緒，線上程式需要用jstack命令，將當前執行緒的狀態匯出來放到檔案裡邊，然後將檔案上傳到fastthread.io網站上進行分析。
第三種情況，我們看一下棧溢位的另一種情況，這就是棧的StackOverFlow的情況。下面就是一個死迴圈遞迴呼叫。
package oom; /** * @author huangqingshi * @Date 2020-07-18 */ public class StackOFE { public static void stackOverFlowErrorMethod() { stackOverFlowErrorMethod(); } public static void main(String[] args) { stackOverFlowErrorMethod(); } }
執行之後出現的錯誤如下，程式每次遞迴的時候，程式會把資料結果壓入棧，包括裡邊的指標等，這個時候就需要幀棧大一些才能承受住更多的遞迴呼叫。通過-Xss進行設定，上邊的例子需要設定小一些，以分配更多的幀棧，這次是一個幀棧需要記錄程式資料，所以需要更大的值。
/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/bin/java -Xss2m -Dfile.encoding=UTF-8 -classpath /Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/packager.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/tools.jar:/Users/huangqingshi/Downloads/flink-project/target/classes:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-java/1.7.2/flink-java-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-core/1.7.2/flink-core-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-annotations/1.7.2/flink-annotations-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-metrics-core/1.7.2/flink-metrics-core-1.7.2.jar:/Users/huangqingshi/.m2/repository/com/esotericsoftware/kryo/kryo/2.24.0/kryo-2.24.0.jar:/Users/huangqingshi/.m2/repository/com/esotericsoftware/minlog/minlog/1.2/minlog-1.2.jar:/Users/huangqingshi/.m2/repository/org/objenesis/objenesis/2.1/objenesis-2.1.jar:/Users/huangqingshi/.m2/repository/commons-collections/commons-collections/3.2.2/commons-collections-3.2.2.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-compress/1.18/commons-compress-1.18.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-asm/5.0.4-5.0/flink-shaded-asm-5.0.4-5.0.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-lang3/3.3.2/commons-lang3-3.3.2.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-math3/3.5/commons-math3-3.5.jar:/Users/huangqingshi/.m2/repository/org/slf4j/slf4j-api/1.7.15/slf4j-api-1.7.15.jar:/Users/huangqingshi/.m2/repository/com/google/code/findbugs/jsr305/1.3.9/jsr305-1.3.9.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/force-shading/1.7.2/force-shading-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-streaming-java_2.11/1.7.2/flink-streaming-java_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-runtime_2.11/1.7.2/flink-runtime_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-queryable-state-client-java_2.11/1.7.2/flink-queryable-state-client-java_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-hadoop-fs/1.7.2/flink-hadoop-fs-1.7.2.jar:/Users/huangqingshi/.m2/repository/commons-io/commons-io/2.4/commons-io-2.4.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-netty/4.1.24.Final-5.0/flink-shaded-netty-4.1.24.Final-5.0.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-jackson/2.7.9-5.0/flink-shaded-jackson-2.7.9-5.0.jar:/Users/huangqingshi/.m2/repository/commons-cli/commons-cli/1.3.1/commons-cli-1.3.1.jar:/Users/huangqingshi/.m2/repository/org/javassist/javassist/3.19.0-GA/javassist-3.19.0-GA.jar:/Users/huangqingshi/.m2/repository/org/scala-lang/scala-library/2.11.12/scala-library-2.11.12.jar:/Users/huangqingshi/.m2/repository/com/type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oom.StackOFE Exception in thread "main" java.lang.StackOverflowError at oom.StackOFE.stackOverFlowErrorMethod(StackOFE.java:10) at oom.StackOFE.stackOverFlowErrorMethod(StackOFE.java:10) at oom.StackOFE.stackOverFlowErrorMethod(StackOFE.java:10) at oom.StackOFE.stackOverFlowErrorMethod(StackOFE.java:10) at oom.StackOFE.stackOverFlowErrorMethod(StackOFE.java:10) at oom.StackOFE.stackOverFlowErrorMethod(StackOFE.java:10)
遇到上面的情況下，那麼就需要通過jstack將執行緒資料導到檔案進行分析。找到遞迴的點，如果程式就是需要遞迴的次數的話，那麼這個時候就需要增大幀棧的大小以適應程式。
第四種情況，後設資料區域溢位，後設資料區域也成為方法區，儲存著類的相關資訊，常量池，方法描述符，欄位描述符，執行時產生大量的類就會造成這個區域的溢位。我們執行的時候指定一下後設資料區域的大小，設定到idea的VM options裡邊：-XX:MetaspaceSize=10M -XX:MaxMetaspaceSize=30M。
package oom; import net.sf.cglib.proxy.Enhancer; import net.sf.cglib.proxy.MethodInterceptor; import net.sf.cglib.proxy.MethodProxy; import java.lang.reflect.Method; /** * @author huangqingshi * @Date 2020-07-18 */ public class MetaspaceOOM { static class OOMObject{} public static void main(String[] args) { while (true) { Enhancer enhancer = new Enhancer(); enhancer.setSuperclass(OOMObject.class); enhancer.setUseCache(false); enhancer.setCallback(new MethodInterceptor() { public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable { return proxy.invokeSuper(obj, args); } }); enhancer.create(); } } }
執行的結果如下，後設資料資訊溢位了。這種情況產生的原因有： 通過CBLIG大量生成類，導致Meta資訊滿了；JDK7的時候使用String.intern()不當，會產生大量常量資料；載入大量的jsp以及動態生成jsp檔案。我們需要調整後設資料空間的大小，如果調大了之後還出現了這種異常，我們需要分析哪裡出現的溢位並fix掉。
/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/bin/java -XX:MetaspaceSize=10M -XX:MaxMetaspaceSize=30M -Dfile.encoding=UTF-8 -classpath /Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/packager.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/tools.jar:/Users/huangqingshi/Downloads/flink-project/target/classes:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-java/1.7.2/flink-java-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-core/1.7.2/flink-core-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-annotations/1.7.2/flink-annotations-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-metrics-core/1.7.2/flink-metrics-core-1.7.2.jar:/Users/huangqingshi/.m2/repository/com/esotericsoftware/kryo/kryo/2.24.0/kryo-2.24.0.jar:/Users/huangqingshi/.m2/repository/com/esotericsoftware/minlog/minlog/1.2/minlog-1.2.jar:/Users/huangqingshi/.m2/repository/org/objenesis/objenesis/2.1/objenesis-2.1.jar:/Users/huangqingshi/.m2/repository/commons-collections/commons-collections/3.2.2/commons-collections-3.2.2.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-compress/1.18/commons-compress-1.18.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-asm/5.0.4-5.0/flink-shaded-asm-5.0.4-5.0.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-lang3/3.3.2/commons-lang3-3.3.2.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-math3/3.5/commons-math3-3.5.jar:/Users/huangqingshi/.m2/repository/org/slf4j/slf4j-api/1.7.15/slf4j-api-1.7.15.jar:/Users/huangqingshi/.m2/repository/com/google/code/findbugs/jsr305/1.3.9/jsr305-1.3.9.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/force-shading/1.7.2/force-shading-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-streaming-java_2.11/1.7.2/flink-streaming-java_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-runtime_2.11/1.7.2/flink-runtime_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-queryable-state-client-java_2.11/1.7.2/flink-queryable-state-client-java_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-hadoop-fs/1.7.2/flink-hadoop-fs-1.7.2.jar:/Users/huangqingshi/.m2/repository/commons-io/commons-io/2.4/commons-io-2.4.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-netty/4.1.24.Final-5.0/flink-shaded-netty-4.1.24.Final-5.0.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-jackson/2.7.9-5.0/flink-shaded-jackson-2.7.9-5.0.jar:/Users/huangqingshi/.m2/repository/commons-cli/commons-cli/1.3.1/commons-cli-1.3.1.jar:/Users/huangqingshi/.m2/repository/org/javassist/javassist/3.19.0-GA/javassist-3.19.0-GA.jar:/Users/huangqingshi/.m2/repository/org/scala-lang/scala-library/2.11.12/scala-library-2.11.12.jar:/Users/huangqingshi/.m2/repository/com/typesafe/akka/akka-actor_2.11/2.4.20/akka-actor_2.11-2.4.20.jar:/Users/huangqingshi/.m2/repository/com/typesafe/config/1.3.0/config-1.3.0.jar:/Users/huangqingshi/.m2/repository/org/scala-lang/modules/scala-java8-compat_2.11/0.7.0/scala-java8-compat_2.11-0.7.0.jar:/Users/huangqingshi/.m2/repository/com/typesafe/akka/akka-stream_2.11/2.4.20/akka-stream_2.11-2.4.20.jar:/Users/huangqingshi/.m2/repository/org/reactivestreams/reactive-streams/1.0.0/reactive-streams-1.0.0.jar:/Users/huangqingshi/.m2/repository/com/typesafe/ssl-config-core_2.11/0.2.1/ssl-config-core_2.11-0.2.1.jar:/Users/huangqingshi/.m2/repository/org/scala-lang/modules/scala-parser-combinators_2.11/1.0.4/scala-parser-combinators_2.11-1.0.4.jar:/Users/huangqingshi/.m2/repository/com/typesafe/akka/akka-protobuf_2.11/2.4.20/akka-protobuf_2.11-2.4.20.jar:/Users/huangqingshi/.m2/repository/com/typesafe/akka/akka-slf4j_2.11/2.4.20/akka-slf4j_2.11-2.4.20.jar:/Users/huangqingshi/.m2/repository/org/clapper/grizzled-slf4j_2.11/1.3.2/grizzled-slf4j_2.11-1.3.2.jar:/Users/huangqingshi/.m2/repository/com/github/scopt/scopt_2.11/3.5.0/scopt_2.11-3.5.0.jar:/Users/huangqingshi/.m2/repository/org/xerial/snappy/snappy-java/1.1.4/snappy-java-1.1.4.jar:/Users/huangqingshi/.m2/repository/com/twitter/chill_2.11/0.7.6/chill_2.11-0.7.6.jar:/Users/huangqingshi/.m2/repository/com/twitter/chill-java/0.7.6/chill-java-0.7.6.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-clients_2.11/1.7.2/flink-clients_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-optimizer_2.11/1.7.2/flink-optimizer_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-guava/18.0-5.0/flink-shaded-guava-18.0-5.0.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-connector-kafka-0.10_2.11/1.7.2/flink-connector-kafka-0.10_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-connector-kafka-0.9_2.11/1.7.2/flink-connector-kafka-0.9_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-connector-kafka-base_2.11/1.7.2/flink-connector-kafka-base_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/kafka/kafka-clients/0.10.2.1/kafka-clients-0.10.2.1.jar:/Users/huangqingshi/.m2/repository/net/jpountz/lz4/lz4/1.3.0/lz4-1.3.0.jar:/Users/huangqingshi/.m2/repository/org/slf4j/slf4j-log4j12/1.7.7/slf4j-log4j12-1.7.7.jar:/Users/huangqingshi/.m2/repository/log4j/log4j/1.2.17/log4j-1.2.17.jar:/Users/huangqingshi/.m2/repository/com/alibaba/fastjson/1.2.62/fastjson-1.2.62.jar:/Users/huangqingshi/.m2/repository/com/google/guava/guava/28.1-jre/guava-28.1-jre.jar:/Users/huangqingshi/.m2/repository/com/google/guava/failureaccess/1.0.1/failureaccess-1.0.1.jar:/Users/huangqingshi/.m2/repository/com/google/guava/listenablefuture/9999.0-empty-to-avoid-conflict-with-guava/listenablefuture-9999.0-empty-to-avoid-conflict-with-guava.jar:/Users/huangqingshi/.m2/repository/org/checkerframework/checker-qual/2.8.1/checker-qual-2.8.1.jar:/Users/huangqingshi/.m2/repository/com/google/errorprone/error_prone_annotations/2.3.2/error_prone_annotations-2.3.2.jar:/Users/huangqingshi/.m2/repository/com/google/j2objc/j2objc-annotations/1.3/j2objc-annotations-1.3.jar:/Users/huangqingshi/.m2/repository/org/codehaus/mojo/animal-sniffer-annotations/1.18/animal-sniffer-annotations-1.18.jar:/Users/huangqingshi/.m2/repository/redis/clients/jedis/3.1.0/jedis-3.1.0.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-pool2/2.6.2/commons-pool2-2.6.2.jar:/Users/huangqingshi/.m2/repository/mysql/mysql-connector-java/8.0.16/mysql-connector-java-8.0.16.jar:/Users/huangqingshi/.m2/repository/com/google/protobuf/protobuf-java/3.6.1/protobuf-java-3.6.1.jar:/Users/huangqingshi/.m2/repository/com/alibaba/druid/1.1.20/druid-1.1.20.jar:/Users/huangqingshi/.m2/repository/cglib/cglib/3.2.5/cglib-3.2.5.jar:/Users/huangqingshi/.m2/repository/org/ow2/asm/asm/5.2/asm-5.2.jar:/Users/huangqingshi/.m2/repository/org/apache/ant/ant/1.9.6/ant-1.9.6.jar:/Users/huangqingshi/.m2/repository/org/apache/ant/ant-launcher/1.9.6/ant-launcher-1.9.6.jar oom.MetaspaceOOM Exception in thread "main" java.lang.OutOfMemoryError: Metaspace at net.sf.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:345) at net.sf.cglib.proxy.Enhancer.generate(Enhancer.java:492) at net.sf.cglib.core.AbstractClassGenerator$ClassLoaderData.get(AbstractClassGenerator.java:114) at net.sf.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:291) at net.sf.cglib.proxy.Enhancer.createHelper(Enhancer.java:480) at net.sf.cglib.proxy.Enhancer.create(Enhancer.java:305) at oom.MetaspaceOOM.main(MetaspaceOOM.java:28) Process finished with exit code 1
第五種情況，直接記憶體溢位，我們除了使用堆記憶體外，我們還可能用直接記憶體，即堆外記憶體。NIO為了提高效能，避免在Java Heap和native Heap中切換，所以使用直接記憶體，預設情況下，直接記憶體的大小和對記憶體大小一致。堆外記憶體不受JVM的限制，但是受制於機器整體記憶體的大小限制。如下程式碼設定堆最大記憶體為128m，直接記憶體為100m，然後我們每次分配1M放到list裡邊。
-Xmx128m -XX:MaxDirectMemorySize=100M package oom; import java.nio.ByteBuffer; import java.util.ArrayList; import java.util.List; /** * @author huangqingshi * @Date 2020-07-18 */ public class DirectBufferOOM { public static void main(String[] args) { final int _1M = 1024 * 1024 * 1; List<ByteBuffer> buffers = new ArrayList<>(); int count = 1; while (true) { ByteBuffer byteBuffer = ByteBuffer.allocateDirect(_1M); buffers.add(byteBuffer); System.out.println(count++); } } }
這個時候，當輸出100次的時候，下次再分配的時候會報OOM-Direct buffer memory。
/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/bin/java -Xmx128m -XX:MaxDirectMemorySize=100M -Dfile.encoding=UTF-8 -classpath /Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/packager.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home/lib/tools.jar:/Users/huangqingshi/Downloads/flink-project/target/classes:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-java/1.7.2/flink-java-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-core/1.7.2/flink-core-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-annotations/1.7.2/flink-annotations-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-metrics-core/1.7.2/flink-metrics-core-1.7.2.jar:/Users/huangqingshi/.m2/repository/com/esotericsoftware/kryo/kryo/2.24.0/kryo-2.24.0.jar:/Users/huangqingshi/.m2/repository/com/esotericsoftware/minlog/minlog/1.2/minlog-1.2.jar:/Users/huangqingshi/.m2/repository/org/objenesis/objenesis/2.1/objenesis-2.1.jar:/Users/huangqingshi/.m2/repository/commons-collections/commons-collections/3.2.2/commons-collections-3.2.2.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-compress/1.18/commons-compress-1.18.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-asm/5.0.4-5.0/flink-shaded-asm-5.0.4-5.0.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-lang3/3.3.2/commons-lang3-3.3.2.jar:/Users/huangqingshi/.m2/repository/org/apache/commons/commons-math3/3.5/commons-math3-3.5.jar:/Users/huangqingshi/.m2/repository/org/slf4j/slf4j-api/1.7.15/slf4j-api-1.7.15.jar:/Users/huangqingshi/.m2/repository/com/google/code/findbugs/jsr305/1.3.9/jsr305-1.3.9.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/force-shading/1.7.2/force-shading-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-streaming-java_2.11/1.7.2/flink-streaming-java_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-runtime_2.11/1.7.2/flink-runtime_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-queryable-state-client-java_2.11/1.7.2/flink-queryable-state-client-java_2.11-1.7.2.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-hadoop-fs/1.7.2/flink-hadoop-fs-1.7.2.jar:/Users/huangqingshi/.m2/repository/commons-io/commons-io/2.4/commons-io-2.4.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-netty/4.1.24.Final-5.0/flink-shaded-netty-4.1.24.Final-5.0.jar:/Users/huangqingshi/.m2/repository/org/apache/flink/flink-shaded-jackson/2.7.9-5.0/flink-shaded-jackson-2.7.9-5.0.jar:/Users/huangqingshi/.m2/repository/commons-cli/commons-cli/1.3.1/commons-cli-1.3.1.jar:/Users/huangqingshi/.m2/repository/org/javassist/javassist/3.19.0-GA/javassist-3.19.0-GA.jar:/Users/huangqingshi/.m2/repository/org/scala-lang/scala-library/2.11.12/scala-library-2.11.12.jar:/Users/huangqingshi/.m2/repository/com/type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oom.DirectBufferOOM 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 Exception in thread "main" java.lang.OutOfMemoryError: Direct buffer memory at java.nio.Bits.reserveMemory(Bits.java:694) at java.nio.DirectByteBuffer.<init>(DirectByteBuffer.java:123) at java.nio.ByteBuffer.allocateDirect(ByteBuffer.java:311) at oom.DirectBufferOOM.main(DirectBufferOOM.java:18) Process finished with exit code 1
這種情況是我們使用直接記憶體造成溢位，這個時候我們需要檢查一下程式裡邊是否使用的NIO及NIO，比如Netty，裡邊的直接記憶體的配置。
第6種情況，JDK1.6之後新增了一個錯誤型別，如果堆記憶體太小的時候會報這個錯誤。如果98%的GC的時候回收不到2%的時候會報這個錯誤，也就是最小最大記憶體出現了問題的時候會報這個錯誤。如果程式碼配置了最小最大堆記憶體都為10m。
-Xmx10m -Xms10m package oom; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; /** * @author huangqingshi * @Date 2020-07-18 */ public class GCOverheadOOM { public static void main(String[] args) { ExecutorService executor = Executors.newFixedThreadPool(5); for (int i = 0; i < Integer.MAX_VALUE; i++) { executor.execute(() -> { try { Thread.sleep(10000); } catch (InterruptedException e) { //do nothing } }); } } }
這個我們建立了一個執行緒池，如果執行緒池執行的時候如果核心執行緒處理不過來的時候會把資料放到LinkedBlockingQueue裡邊，也就是堆記憶體當中。這個時候我們需要檢查-Xms -Xmx最小最大堆配置是否合理。再一個dump出現當前記憶體來分析一下是否使用了大量的迴圈或使用大量記憶體程式碼。
以上就是我們經常遇到的情況，我們需要針對出現的不行情況進行分析和處理。