Jetty提供的執行緒池相關的模組，如下：
threadpoolthreadpool-virtual，使用JDK 21提供的virtual threads。threadpool-virtual-preview，使用JDK 19和JDK 20。
注意上述模組不能共存。
啟用threadpool模組後再啟用threadpool-virtual模組時，將會有類似如下的提示：
ERROR : Module threadpool-virtual provides threadpool, which is already provided by threadpool enabled in [${jetty.base}/start.d/threadpool.ini]
Usage: java -jar $JETTY_HOME/start.jar [options] [properties] [configs]
java -jar $JETTY_HOME/start.jar --help # for more information
threadpool
啟用threadpool模組，執行如下命令：
java -jar $JETTY_HOME/start.jar --add-modules=threadpool
命令的輸出，如下：
INFO : threadpool initialized in ${jetty.base}/start.d/threadpool.ini
INFO : Base directory was modified
threadpool模組的配置檔案$JETTY_BASE/start.d/threadpool.ini，內容如下：
# ---------------------------------------
# Module: threadpool
# Enables and configures the Server ThreadPool.
# ---------------------------------------
--modules=threadpool
## Thread name prefix.
#jetty.threadPool.namePrefix=qtp<hashCode>
## Minimum number of pooled threads.
#jetty.threadPool.minThreads=10
## Maximum number of pooled threads.
#jetty.threadPool.maxThreads=200
## Number of reserved threads (-1 for heuristic).
#jetty.threadPool.reservedThreads=-1
## Whether to use virtual threads, if the runtime supports them.
## Deprecated, use Jetty module 'threadpool-virtual' instead.
#jetty.threadPool.useVirtualThreads=false
## Thread idle timeout (in milliseconds).
#jetty.threadPool.idleTimeout=60000
## The max number of idle threads that are evicted in one idleTimeout period.
#jetty.threadPool.maxEvictCount=1
## Whether to output a detailed dump.
#jetty.threadPool.detailedDump=false
各引數的說明，如下：
jetty.threadPool.namePrefix
執行緒池中各執行緒的名稱字首。jetty.threadPool.minThreads
執行緒池中執行緒的最小數量。jetty.threadPool.maxThreads
執行緒池中執行緒的最大數量。jetty.threadPool.reservedThreads
執行緒池中保留的執行緒的數量。jetty.threadPool.useVirtualThreads
不推薦使用。對於JDK 21，推薦使用threadpool-virtual模組。jetty.threadPool.idleTimeout
空閒執行緒從執行緒池中移除前等待的時長，單位：毫秒，預設值：60000，即60秒。jetty.threadPool.maxEvictCount
清理空閒執行緒時，單次操作中被移除掉的執行緒的數量。jetty.threadPool.detailedDump
是否匯出執行緒池中各執行緒的完整的棧。預設值為false，即只輸出棧頂。
threadpool-virtual
啟用threadpool-virtual模組，執行如下命令：
java -jar $JETTY_HOME/start.jar --add-modules=threadpool-virtual
啟用threadpool-virtual模組成功時的輸出，如下：
INFO : threadpool-virtual initialized in ${jetty.base}/start.d/threadpool-virtual.ini
INFO : Base directory was modified
threadpool-virtual模組的配置檔案$JETTY_BASE/start.d/threadpool-virtual.ini，內容如下：
# ---------------------------------------
# Module: threadpool-virtual
# Enables and configures the Server ThreadPool with support for virtual threads in Java 21 or later.
# ---------------------------------------
--modules=threadpool-virtual
## Platform threads name prefix.
#jetty.threadPool.namePrefix=qtp<hashCode>
## Minimum number of pooled threads.
#jetty.threadPool.minThreads=10
## Maximum number of pooled threads.
#jetty.threadPool.maxThreads=200
## Number of reserved threads (-1 for heuristic).
#jetty.threadPool.reservedThreads=-1
## Thread idle timeout (in milliseconds).
#jetty.threadPool.idleTimeout=60000
## The max number of idle threads that can be evicted in one idleTimeout period.
#jetty.threadPool.maxEvictCount=1
## Whether to output a detailed dump.
#jetty.threadPool.detailedDump=false
## Virtual threads name prefix.
#jetty.threadPool.virtual.namePrefix=qtp<hashCode>-virtual-
## Whether virtual threads inherits the values of inheritable thread locals.
#jetty.threadPool.virtual.inheritInheritableThreadLocals=true
各引數的說明，如下：
jetty.threadPool.namePrefix
同threadPool。jetty.threadPool.minThreads
同threadPool。jetty.threadPool.maxThreads
同threadPool。jetty.threadPool.reservedThreads
同threadPool。jetty.threadPool.idleTimeout
同threadPool。jetty.threadPool.maxEvictCount
同threadPool。jetty.threadPool.detailedDump
同threadPool。jetty.threadPool.virtual.namePrefix
virtual threads的執行緒名稱的字首。jetty.threadPool.virtual.inheritInheritableThreadLocals
是否複用ThreadLocal物件。預設值為true。
threadpool-virtual-preview
啟用threadpool-virtual-preview模組，執行如下命令：
java -jar $JETTY_HOME/start.jar --add-modules=threadpool-virtual-preview
啟用threadpool-virtual-preview模組成功時的輸出，如下：
INFO : threadpool-virtual-preview initialized in ${jetty.base}/start.d/threadpool-virtual-preview.ini
INFO : Base directory was modified
threadpool-virtual-preview模組的配置檔案$JETTY_BASE/start.d/threadpool-virtual-preview.ini，內容如下：
# ---------------------------------------
# Module: threadpool-virtual-preview
# Enables and configures the Server ThreadPool with support for virtual threads in Java 19 and Java 20.
# ---------------------------------------
--modules=threadpool-virtual-preview
## Platform threads name prefix.
#jetty.threadPool.namePrefix=qtp<hashCode>
## Minimum number of pooled threads.
#jetty.threadPool.minThreads=10
## Maximum number of pooled threads.
#jetty.threadPool.maxThreads=200
## Number of reserved threads (-1 for heuristic).
#jetty.threadPool.reservedThreads=-1
## Thread idle timeout (in milliseconds).
#jetty.threadPool.idleTimeout=60000
## The max number of idle threads that can be evicted in one idleTimeout period.
#jetty.threadPool.maxEvictCount=1
## Whether to output a detailed dump.
#jetty.threadPool.detailedDump=false
## Virtual threads name prefix.
#jetty.threadPool.virtual.namePrefix=qtp<hashCode>-virtual-
## Whether virtual threads are allowed to set thread locals.
#jetty.threadPool.virtual.allowSetThreadLocals=true
## Whether virtual threads inherits the values of inheritable thread locals.
#jetty.threadPool.virtual.inheritInheritableThreadLocals=true
各引數的說明，如下：
jetty.threadPool.namePrefix
同threadPool。jetty.threadPool.minThreads
同threadPool。jetty.threadPool.maxThreads
同threadPool。jetty.threadPool.reservedThreads
同threadPool。jetty.threadPool.idleTimeout
同threadPool。jetty.threadPool.maxEvictCount
同threadPool。jetty.threadPool.detailedDump
同threadPool。jetty.threadPool.virtual.namePrefix
virtual threads的執行緒名稱的字首。jetty.threadPool.virtual.allowSetThreadLocals
是否允許virtual threads記錄ThreadLocal型別的物件。預設值為true。jetty.threadPool.virtual.inheritInheritableThreadLocals
是否複用ThreadLocal物件。預設值為true。
參考資料
- 虛擬執行緒原理及效能分析
- 聊一聊JDK21-虛擬執行緒
- Java高併發革命！JDK19新特性——虛擬執行緒（Virtual Threads）
- Virtual Threads 虛擬執行緒