[ConsoleProxy] Performance fixes on concurrency and closing console sessions sockets by nvazquez · Pull Request #13683 · apache/cloudstack

nvazquez · 2026-07-24T03:04:38Z

Description

This PR addresses 2 issues:

In case of concurrent console proxy requests, 2 different threads could modify the allowedSessions set and cause problems accessing the console sessions (fix to be verified)
After closing the browser tab for a VM console session, it was observed that the connection remained open on the KVM host's VNC port.
- Before the fix: After opening multiple sessions for the same VM, each new session opens a new socket connection on the KVM host on the VNC port but was not closed after closing the console browser tab.

[root@ref-trl-12127-k-Mol9-nicolas-vazquez-kvm2 ~]# ss -tnp | grep 5901
ESTAB 0      55              10.0.33.112:5901           10.0.39.91:43024 users:(("qemu-kvm",pid=77212,fd=38))                                     
ESTAB 0      55              10.0.33.112:5901           10.0.39.91:51796 users:(("qemu-kvm",pid=77212,fd=36))                                     
ESTAB 0      0               10.0.33.112:5901           10.0.39.91:43008 users:(("qemu-kvm",pid=77212,fd=37))                                     
ESTAB 0      0               10.0.33.112:5901           10.0.39.91:60794 users:(("qemu-kvm",pid=77212,fd=35))

After the fix: Each time a console session is acquired, then only one socket connection remains open per VM, and when it is closed then no connections remain open:

[root@ref-trl-12127-k-Mol9-nicolas-vazquez-kvm2 ~]# ss -tnp | grep 5901
[root@ref-trl-12127-k-Mol9-nicolas-vazquez-kvm2 ~]# ss -tnp | grep 5901
ESTAB 0      0               10.0.33.112:5901           10.0.39.99:41826 users:(("qemu-kvm",pid=77212,fd=35))                                     
[root@ref-trl-12127-k-Mol9-nicolas-vazquez-kvm2 ~]# ss -tnp | grep 5901
[root@ref-trl-12127-k-Mol9-nicolas-vazquez-kvm2 ~]# ss -tnp | grep 5901
ESTAB 0      0               10.0.33.112:5901           10.0.39.99:36836 users:(("qemu-kvm",pid=77212,fd=35))

Fixes: #13422

Types of changes

Breaking change (fix or feature that would cause existing functionality to change)
New feature (non-breaking change which adds functionality)
Bug fix (non-breaking change which fixes an issue)
Enhancement (improves an existing feature and functionality)
Cleanup (Code refactoring and cleanup, that may add test cases)
Build/CI
Test (unit or integration test code)

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

Major
Minor

Bug Severity

Screenshots (if appropriate):

How Has This Been Tested?

Replaced the agent.zip file on /usr/share/cloudstack-common/vms/ for each KVM host and recreated the CPVM
Acquired multiple console sessions and verified the the established using the ss -tnp command for VM's VNC ports

How did you try to break this feature and the system with this change?

Copilot

Pull request overview

This PR targets ConsoleProxy reliability and resource usage by (1) making the “allowed sessions” tracking safe under concurrent access, and (2) ensuring VNC-related connections are actively closed when a noVNC browser session ends, preventing lingering sockets on KVM hosts.

Changes:

Introduces explicit close paths for NIO socket resources and noVNC client connections to avoid leaking VNC sockets.
Makes ConsoleProxy.allowedSessions concurrency-safe and guards one-time session consumption.
Ensances WebSocket close handling to trigger client teardown and make remote-address logging more robust.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
services/console-proxy/server/src/main/java/com/cloud/consoleproxy/vnc/NoVncClient.java	Adds a `close()` method to shut down NIO, websocket, and tunnel socket resources.
services/console-proxy/server/src/main/java/com/cloud/consoleproxy/vnc/network/NioSocketHandlerImpl.java	Stores the underlying `NioSocket` and exposes `close()` to release it.
services/console-proxy/server/src/main/java/com/cloud/consoleproxy/vnc/network/NioSocketHandler.java	Adds a `close()` contract to the handler interface.
services/console-proxy/server/src/main/java/com/cloud/consoleproxy/vnc/network/NioSocket.java	Adds a `close()` method to release the socket channel and selectors.
services/console-proxy/server/src/main/java/com/cloud/consoleproxy/ConsoleProxyNoVNCHandler.java	Ensures viewer teardown is triggered on WebSocket close and hardens remote-address logging.
services/console-proxy/server/src/main/java/com/cloud/consoleproxy/ConsoleProxyNoVncClient.java	Ensures `closeClient()` closes the underlying `NoVncClient` before removing the viewer.
services/console-proxy/server/src/main/java/com/cloud/consoleproxy/ConsoleProxy.java	Switches `allowedSessions` to a concurrent set and synchronizes one-time session consumption; uses `closeClient()` when replacing viewers.

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+    public void close() {
+        if (nioSocketConnection != null) {
+            nioSocketConnection.close();
+        }
+        if (webSocketReverseProxy != null) {
+            webSocketReverseProxy.close();
+        }
+        if (socket != null) {
+            try {
+                if (is != null) {
+                    is.close();
+                }
+                if (os != null) {
+                    os.close();
+                }
+                socket.close();
+            } catch (IOException e) {
+                logger.debug("Error closing socket: " + e.getMessage(), e);
+            }
+        }
+    }


+        synchronized (allowedSessionsLock) {
+            if (allowedSessions.contains(sessionUuid)) {
+                LOGGER.debug("Acquiring the session " + sessionUuid + " not available for future use");
+                allowedSessions.remove(sessionUuid);
+            } else {
+                LOGGER.info("Session " + sessionUuid + " has already been used, cannot connect");
+                authResult.setSuccess(false);
+                return authResult;
+            }
        }


    public void closeClient() {
        this.connectionAlive = false;
        // Clear buffer reference to allow GC when client disconnects
        this.readBuffer = null;
+        if (client != null) {
+            client.close();
+        }
        ConsoleProxy.removeViewer(this);


codecov · 2026-07-24T03:13:23Z

Codecov Report

❌ Patch coverage is 3.22581% with 60 lines in your changes missing coverage. Please review.
✅ Project coverage is 17.69%. Comparing base (0339f31) to head (08a76ba).

Files with missing lines	Patch %	Lines
.../com/cloud/consoleproxy/vnc/network/NioSocket.java	0.00%	20 Missing ⚠️
...n/java/com/cloud/consoleproxy/vnc/NoVncClient.java	0.00%	16 Missing ⚠️
...m/cloud/consoleproxy/ConsoleProxyNoVNCHandler.java	0.00%	10 Missing ⚠️
...main/java/com/cloud/consoleproxy/ConsoleProxy.java	20.00%	8 Missing ⚠️
...consoleproxy/vnc/network/NioSocketHandlerImpl.java	0.00%	4 Missing ⚠️
...om/cloud/consoleproxy/ConsoleProxyNoVncClient.java	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               4.22   #13683      +/-   ##
============================================
- Coverage     17.69%   17.69%   -0.01%     
  Complexity    15833    15833              
============================================
  Files          5925     5925              
  Lines        533534   533585      +51     
  Branches      65273    65282       +9     
============================================
- Hits          94421    94417       -4     
- Misses       428434   428492      +58     
+ Partials      10679    10676       -3

Flag	Coverage Δ
uitests	`3.69% <ø> (ø)`
unittests	`18.77% <3.22%> (-0.01%)`	⬇️

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nvazquez · 2026-07-24T03:22:54Z

@blueorangutan package

blueorangutan · 2026-07-24T03:24:04Z

@nvazquez a [SL] Jenkins job has been kicked to build packages. It will be bundled with KVM, XenServer and VMware SystemVM templates. I'll keep you posted as I make progress.

blueorangutan · 2026-07-24T04:22:20Z

Packaging result [SF]: ✔️ el8 ✔️ el9 ✔️ el10 ✔️ debian ✔️ suse15. SL-JID 18654

DaanHoogland

clgtm

Pearl1594 · 2026-07-24T16:07:52Z

+                LOGGER.info("Session " + sessionUuid + " has already been used, cannot connect");
+                authResult.setSuccess(false);
+                return authResult;
+            }


Pearl1594

code lgtm

nvazquez added 2 commits July 23, 2026 23:33

Add lock and synchronize allowed sessions

9453345

Fix closing connections to VNC ports on console close

08a76ba

nvazquez added this to the 4.22.2 milestone Jul 24, 2026

nvazquez requested review from Pearl1594, Copilot, shwstppr and sureshanaparti July 24, 2026 03:04

nvazquez added type:bug component:console-proxy labels Jul 24, 2026

Copilot started reviewing on behalf of nvazquez July 24, 2026 03:05 View session

Copilot AI reviewed Jul 24, 2026

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DaanHoogland linked an issue Jul 24, 2026 that may be closed by this pull request

Intermittent Console Proxy Failure in 4.22.1.0 #13422

Open

DaanHoogland approved these changes Jul 24, 2026

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DaanHoogland added the status:needs-testing label Jul 24, 2026

Pearl1594 reviewed Jul 24, 2026

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Pearl1594 approved these changes Jul 24, 2026

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[ConsoleProxy] Performance fixes on concurrency and closing console sessions sockets#13683

[ConsoleProxy] Performance fixes on concurrency and closing console sessions sockets#13683
nvazquez wants to merge 2 commits into
apache:4.22from
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nvazquez commented Jul 24, 2026

Description

Types of changes

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

Bug Severity

Screenshots (if appropriate):

How Has This Been Tested?

How did you try to break this feature and the system with this change?

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Pull request overview

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codecov Bot commented Jul 24, 2026 •

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