From b971e97474415c81c4cd1919b86fd24245df6008 Mon Sep 17 00:00:00 2001
From: laishenghao <laishenghao1@huawei.com>
Date: Tue, 27 Jun 2023 20:52:00 +0800
Subject: [PATCH] =?UTF-8?q?=E8=A7=A3=E5=86=B3=E5=B9=B6=E8=A1=8C=E5=88=9B?=
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---
 .../process/postmaster/bgworker.cpp           | 43 +++++++++++++++++--
 1 file changed, 39 insertions(+), 4 deletions(-)

diff --git a/src/gausskernel/process/postmaster/bgworker.cpp b/src/gausskernel/process/postmaster/bgworker.cpp
index bcb5522d0..e9a3dc917 100644
--- a/src/gausskernel/process/postmaster/bgworker.cpp
+++ b/src/gausskernel/process/postmaster/bgworker.cpp
@@ -364,6 +364,7 @@ bool RegisterBackgroundWorker(BgWorkerContext *bwc)
     BGW_HDR* bgworker_base = (BGW_HDR *)g_instance.bgw_base;
     BackgroundWorker *bgw = NULL;
     BackgroundWorkerArgs *bwa = NULL;
+    Backend* bn = nullptr;
 
     /* Construct bgworker thread args */
     bwa = (BackgroundWorkerArgs*)MemoryContextAllocZero(
@@ -387,15 +388,49 @@ bool RegisterBackgroundWorker(BgWorkerContext *bwc)
     bwa->bgworker = bgw;
     bwa->bgworkerId = bgw->bgw_id;
 
-    /* Fork a new worker thread */
-    bgw->bgw_notify_pid = initialize_util_thread(BGWORKER, bwa);
-    /* failed to fork a new thread */
-    if (bgw->bgw_notify_pid == 0) {
+    int slot = AssignPostmasterChildSlot();
+    if (slot == -1) {
         pfree_ext(bwa);
         BgworkerPutBackToFreeList(bgw);
         return false;
     }
 
+    bn  = AssignFreeBackEnd(slot);
+    int thisChildSlot = t_thrd.proc_cxt.MyPMChildSlot;
+    if (bn) {
+        GenerateCancelKey(false);
+        bn->cancel_key = t_thrd.proc_cxt.MyCancelKey;
+        bn->child_slot = t_thrd.proc_cxt.MyPMChildSlot = slot;
+        bn->role = BGWORKER;
+    } else {
+        ReleasePostmasterChildSlot(slot);
+        pfree_ext(bwa);
+        BgworkerPutBackToFreeList(bgw);
+        ereport(LOG, (errcode(ERRCODE_LOG), errmsg("assign backend failed in RegisterBackgroundWorker")));
+        return false;
+    }
+
+    /* Fork a new worker thread */
+    bgw->bgw_notify_pid = initialize_util_thread(BGWORKER, bwa);
+    t_thrd.proc_cxt.MyPMChildSlot = thisChildSlot;
+
+    /* failed to fork a new thread */
+    if (bgw->bgw_notify_pid == 0) {
+        pfree_ext(bwa);
+        BgworkerPutBackToFreeList(bgw);
+        ReleasePostmasterChildSlot(slot);
+
+        bn->pid = 0;
+        bn->role = (knl_thread_role)0;
+        bn = nullptr;
+        return false;
+    }
+
+    bn->pid = bgw->bgw_notify_pid;
+    bn->is_autovacuum = false;
+    DLInitElem(&bn->elem, bn);
+    DLAddHead(g_instance.backend_list, &bn->elem);
+
     if (g_threadPoolControler) {
         // Try to bind thread to available CPUs in threadpool
         g_threadPoolControler->BindThreadToAllAvailCpu(bgw->bgw_notify_pid);