!1484 修复twophasecleaner内存泄漏

Merge pull request !1484 from maxiang/master_twophase

src/gausskernel/process/postmaster/twophasecleaner.cpp

@@ -131,6 +131,19 @@ NON_EXEC_STATIC void TwoPhaseCleanerMain()
     /* We allow SIGQUIT (quickdie) at all times */
     (void)sigdelset(&t_thrd.libpq_cxt.BlockSig, SIGQUIT);
 
+    /*
+     * Create a memory context that we will do all our work in.  We do this so
+     * that we can reset the context during error recovery and thereby avoid
+     * possible memory leaks.  Formerly this code just ran in
+     * t_thrd.top_mem_cxt, but resetting that would be a really bad idea.
+     */
+    twopc_context = AllocSetContextCreate(t_thrd.top_mem_cxt,
+        "TwoPhase Cleaner",
+        ALLOCSET_DEFAULT_MINSIZE,
+        ALLOCSET_DEFAULT_INITSIZE,
+        ALLOCSET_DEFAULT_MAXSIZE);
+    (void)MemoryContextSwitchTo(twopc_context);
+
     /*
      * If an exception is encountered, processing resumes here.
      *
@@ -146,8 +159,18 @@ NON_EXEC_STATIC void TwoPhaseCleanerMain()
         /* Report the error to the server log */
         EmitErrorReport();
 
+
+        /*
+         * Now return to normal top-level context and clear ErrorContext for
+         * next time.
+         */
+        (void)MemoryContextSwitchTo(twopc_context);
+
         FlushErrorState();
 
+        /* Flush any leaked data in the top-level context */
+        MemoryContextResetAndDeleteChildren(twopc_context);
+
         /* Now we can allow interrupts again */
         RESUME_INTERRUPTS();
     }
@@ -156,19 +179,6 @@ NON_EXEC_STATIC void TwoPhaseCleanerMain()
     /* We can now handle ereport(ERROR) */
     t_thrd.log_cxt.PG_exception_stack = &local_sigjmp_buf;
 
-    /*
-     * Create a memory context that we will do all our work in.  We do this so
-     * that we can reset the context during error recovery and thereby avoid
-     * possible memory leaks.  Formerly this code just ran in
-     * t_thrd.top_mem_cxt, but resetting that would be a really bad idea.
-     */
-    twopc_context = AllocSetContextCreate(t_thrd.top_mem_cxt,
-        "TwoPhase Cleaner",
-        ALLOCSET_DEFAULT_MINSIZE,
-        ALLOCSET_DEFAULT_INITSIZE,
-        ALLOCSET_DEFAULT_MAXSIZE);
-    (void)MemoryContextSwitchTo(twopc_context);
-
     /* Unblock signals (they were blocked when the postmaster forked us) */
     gs_signal_setmask(&t_thrd.libpq_cxt.UnBlockSig, NULL);
     (void)gs_signal_unblock_sigusr2();
@@ -285,6 +295,8 @@ NON_EXEC_STATIC void TwoPhaseCleanerMain()
         pgstat_report_activity(STATE_IDLE, NULL);
         rc = WaitLatch(&t_thrd.proc->procLatch, WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH, (long)10000 /* 10s */);
 
+        MemoryContextResetAndDeleteChildren(twopc_context);
+
         /*
          * Emergency bailout if postmaster has died.  This is to avoid the
          * necessity for manual cleanup of all postmaster children.