From 017c51c246179321f0857e6ebe566d6d66ef6c94 Mon Sep 17 00:00:00 2001
From: byigorv <60062354+byigorv@users.noreply.github.com>
Date: Fri, 24 Mar 2023 08:52:37 +0300
Subject: [PATCH] fix mem leak in hubConnectionIndex (#22560)

---
 server/channels/app/platform/web_hub.go      |  2 ++
 server/channels/app/platform/web_hub_test.go | 37 ++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/server/channels/app/platform/web_hub.go b/server/channels/app/platform/web_hub.go
index d37f3d4762..02652adf58 100644
--- a/server/channels/app/platform/web_hub.go
+++ b/server/channels/app/platform/web_hub.go
@@ -599,6 +599,8 @@ func (i *hubConnectionIndex) Remove(wc *WebConn) {
 	last := userConnections[len(userConnections)-1]
 	// set the slot that we are trying to remove to be the last connection.
 	userConnections[userConnIndex] = last
+	// remove the last connection pointer from slice.
+	userConnections[len(userConnections)-1] = nil
 	// remove the last connection from the slice.
 	i.byUserId[wc.UserId] = userConnections[:len(userConnections)-1]
 	// set the index of the connection that was moved to the new index.
diff --git a/server/channels/app/platform/web_hub_test.go b/server/channels/app/platform/web_hub_test.go
index 10db2fcb7c..0fc45e730c 100644
--- a/server/channels/app/platform/web_hub_test.go
+++ b/server/channels/app/platform/web_hub_test.go
@@ -8,6 +8,7 @@ import (
 	"net"
 	"net/http"
 	"net/http/httptest"
+	"runtime"
 	"testing"
 	"time"
 
@@ -539,6 +540,42 @@ func BenchmarkHubConnIndex(b *testing.B) {
 	})
 }
 
+func TestHubConnIndexRemoveMemLeak(t *testing.T) {
+	th := Setup(t)
+	defer th.TearDown()
+
+	connIndex := newHubConnectionIndex(1 * time.Second)
+
+	wc := &WebConn{
+		Platform: th.Service,
+		Suite:    th.Suite,
+	}
+	wc.SetConnectionID(model.NewId())
+	wc.SetSession(&model.Session{})
+
+	ch := make(chan struct{})
+
+	runtime.SetFinalizer(wc, func(*WebConn) {
+		close(ch)
+	})
+
+	connIndex.Add(wc)
+	connIndex.Remove(wc)
+
+	runtime.GC()
+
+	timer := time.NewTimer(3 * time.Second)
+	defer timer.Stop()
+
+	select {
+	case <-ch:
+	case <-timer.C:
+		require.Fail(t, "timeout waiting for collection of wc")
+	}
+
+	assert.Len(t, connIndex.byConnection, 0)
+}
+
 var hubSink *Hub
 
 func BenchmarkGetHubForUserId(b *testing.B) {