Shared Server Processes (Snnn) (131)

Each shared server process serves multiple client requests in the shared server
configuration. Shared server processes and dedicated server processes provide the
same functionality, except shared server processes are not associated with a specific
user process. Instead, a shared server process serves any client request in the shared
server configuration.
The PGA of a shared server process does not contain user-related data (which needs to
be accessible to all shared server processes). The PGA of a shared server process
contains only stack space and process-specific variables.
All session-related information is contained in the SGA. Each shared server process
needs to be able to access all sessions’ data spaces so that any server can handle
requests from any session. Space is allocated in the SGA for each session’s data space.
You can limit the amount of space that a session can allocate by setting the resource
limit PRIVATE_SGA to the desired amount of space in the user’s profile.
Oracle dynamically adjusts the number of shared server processes based on the length
of the request queue. The number of shared server processes that can be created ranges
between the values of the initialization parameters SHARED_SERVERS and MAX_SHARED_SERVERS.

共享服務程式
1. pga中的共享服務程式不包括使用者相關的資料 , 包括的是堆疊空間和程式相關變數
2. 所有會話相關的程式都包含在SGA中 .
3. 透過使用者資源配置檔案中的PRIVATE_SGA引數可以限定會話在sga可被分配的總空間
4. Oracle可以動態調整共享伺服器程式的數目 , 也可以透過引數指定 , 值在SHARED_SERVERS和MAX_SHARED_SERVERS之間

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