PostgreSQL神秘进程的观察

在PostgreSQL运行的时候，通过对其代码进行跟踪，发现不断有进程被生成，访问InitFileAccess，过了大约20秒左右，就死掉了。

这个过程反复地进行着，进程号不断增加。

我对其进一步进行了跟踪，发现似乎是这些进程是为了 autovacuum 而被创建出来，然后自己消亡的。

在PostgreSQL9.2源代码中加入：

InitFileAccess(void)

{



    fprintf(stderr,"In %s ...by Process %d\n", __FUNCTION__,getpid());

    fprintf(stderr,"----------------------------------------------------\n\n");



    ...

}

void

BaseInit(void)

{



    fprintf(stderr,"In %s ...by Process %d\n", __FUNCTION__,getpid());



    /*

     * Attach to shared memory and semaphores, and initialize our

     * input/output/debugging file descriptors.

     */

    InitCommunication();

    DebugFileOpen();



    /* Do local initialization of file, storage and buffer managers */

    InitFileAccess();

    smgrinit();

    InitBufferPoolAccess();

}

NON_EXEC_STATIC void

AutoVacLauncherMain(int argc, char *argv[])

{

    ...

    fprintf(stderr,"In %s ...by Process %d\n", __FUNCTION__,getpid());



    /* Early initialization */

    BaseInit();

    ...

    proc_exit(0);                /* done */

}

NON_EXEC_STATIC void

AutoVacWorkerMain(int argc, char *argv[])

{

    ...

    fprintf(stderr,"In %s ...by Process %d\n", __FUNCTION__,getpid());



    /* Early initialization */

    BaseInit();

    ...



    /* All done, go away */

    proc_exit(0);

}

 

执行结果如下：

[postgres@lex bin]$ ./pg_ctl -D ../data start

server starting

[postgres@lex bin]$ In BaseInit ...by Process 4804

In InitFileAccess ...by Process 4804

----------------------------------------------------



LOG:  database system was shut down at 2013-05-24 14:29:46 CST

In BaseInit ...by Process 4805

In InitFileAccess ...by Process 4805

----------------------------------------------------



In BaseInit ...by Process 4806

In InitFileAccess ...by Process 4806

----------------------------------------------------



In BaseInit ...by Process 4807

In InitFileAccess ...by Process 4807

----------------------------------------------------



LOG:  autovacuum launcher started

In AutoVacLauncherMain ...by Process 4808

In BaseInit ...by Process 4808

In InitFileAccess ...by Process 4808

----------------------------------------------------



LOG:  database system is ready to accept connections

In AutoVacWorkerMain ...by Process 4816

In BaseInit ...by Process 4816

In InitFileAccess ...by Process 4816

----------------------------------------------------



In AutoVacWorkerMain ...by Process 4823

In BaseInit ...by Process 4823

In InitFileAccess ...by Process 4823

----------------------------------------------------



In AutoVacWorkerMain ...by Process 4830

In BaseInit ...by Process 4830

In InitFileAccess ...by Process 4830

----------------------------------------------------