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

nvazquez · 2026-07-24T03:04:38Z

Description

This PR addresses 3 issues:

In case of concurrent console proxy requests, 2 different threads could modify the allowedSessions set and cause problems accessing the console sessions\
Connection drop and reconnection failures (Intermittent Console Proxy Failure in 4.22.1.0 #13422): in cases in which a session has been properly acquired but after a few seconds declared as dead and then tried to reconnect, the CPVM prevented it as the session has already been acquired.
- To fix this, a new zone setting is added consoleproxy.session.reconnection.window with default value = 0, which sets a reconnection window for the same client IP once a connection is declared as dead.
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
Using the default value consoleproxy.session.reconnection.window = 0, observe no changes on console sessions reconnection
Set consoleproxy.session.reconnection.window = 5000, recreate CPVM. Observe refreshing the browser tab allows the same client to reclaim back/reconnect to the same session. Also, if another session acquires the console session, the previous session could be reclaimed back within the reconnection window timeframe

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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codecov · 2026-07-24T03:13:23Z

Codecov Report

❌ Patch coverage is 4.80769% with 99 lines in your changes missing coverage. Please review.
✅ Project coverage is 17.69%. Comparing base (0339f31) to head (bfd5d0a).

Files with missing lines	Patch %	Lines
...main/java/com/cloud/consoleproxy/ConsoleProxy.java	8.69%	42 Missing ⚠️
.../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 ⚠️
...consoleproxy/vnc/network/NioSocketHandlerImpl.java	0.00%	4 Missing ⚠️
...om/cloud/consoleproxy/ConsoleProxyManagerImpl.java	0.00%	3 Missing ⚠️
...om/cloud/consoleproxy/ConsoleProxyNoVncClient.java	0.00%	3 Missing ⚠️
...a/com/cloud/consoleproxy/ConsoleProxyGCThread.java	0.00%	1 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   533627      +93     
  Branches      65273    65290      +17     
============================================
- Hits          94421    94419       -2     
- Misses       428434   428531      +97     
+ Partials      10679    10677       -2

Flag	Coverage Δ
uitests	`3.69% <ø> (ø)`
unittests	`18.77% <4.80%> (-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

code lgtm

nvazquez · 2026-07-27T01:16:49Z

Marked on draft as still working on fixing the issues reported on: #13422

…after acquiring a session

Copilot

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

… sessions

nvazquez · 2026-07-28T15:18:17Z

@blueorangutan package

blueorangutan · 2026-07-28T15:20:06Z

@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.

weizhouapache · 2026-07-28T16:00:18Z

+        if (grant.clientIp != null && !grant.clientIp.equals(clientIp)) {
+            LOGGER.warn("Rejecting reconnection for session {} as it was requested from IP {} " +
+                    "but the session was granted to IP {}", sessionUuid, clientIp, grant.clientIp);
+            return false;


should "return true" only if client IPs match, and "return false" by default ?

Hi @weizhouapache not only client IPs match but also the reconnection attempt is within the reconnection window/timeframe

blueorangutan · 2026-07-28T16:17:17Z

Packaging result [SF]: ✔️ el8 ✔️ el9 ✔️ el10 ✔️ debian ✔️ suse15. SL-JID 18698

nvazquez · 2026-07-28T16:46:25Z

@blueorangutan test

blueorangutan · 2026-07-28T16:48:04Z

@nvazquez a [SL] Trillian-Jenkins test job (ol8 mgmt + kvm-ol8) has been kicked to run smoke tests

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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Comment thread services/console-proxy/server/src/main/java/com/cloud/consoleproxy/ConsoleProxy.java

Pearl1594 approved these changes Jul 24, 2026

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nvazquez marked this pull request as draft July 27, 2026 01:16

Add reconnection grant window to prevent network connectivity issues …

54d0d7a

…after acquiring a session

nvazquez marked this pull request as ready for review July 27, 2026 15:01

nvazquez requested a review from Copilot July 27, 2026 15:11

Copilot AI reviewed Jul 27, 2026

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Copilot started reviewing on behalf of nvazquez July 27, 2026 16:10 View session

nvazquez marked this pull request as draft July 28, 2026 03:19

Introduce zone setting to control the reconnection window for console…

bfd5d0a

… sessions

nvazquez marked this pull request as ready for review July 28, 2026 15:18

nvazquez changed the title ~~[ConsoleProxy] Performance fixes on concurrency and closing console sessions sockets~~ [ConsoleProxy] Performance fixes on concurrency and closing console sessions sockets and introduce reconnection window for console sessions Jul 28, 2026

weizhouapache reviewed Jul 28, 2026

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Description

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