# Consistent 100% CPU use of safeCall-queue thread **URL:** \ **Category:** Runtime\ **Created:** [January 26, 2023, 1:02am UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792 "2023-01-26T01:02:01Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![ccutrer](https://community.openhab.org/user_avatar/community.openhab.org/ccutrer/32/73828_2.png) [@ccutrer](https://community.openhab.org/u/ccutrer)\ **Post date:** [June 8, 2023, 4:56pm UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/21 "2023-06-08T16:56:28Z")
JSR223 scripts get wrapped in a safeCall, as well as rule executions. I would guess that your “bad” rule caused many many calls to be sent through the safeCall queue, greatly increasing the probability of hitting the race condition in LinkedTransferQueue. Good to know though that if you’re hitting this quite often, it might be because something in your setup is causing it to get triggered more often. ---
**Author:** ![Andrew\_Rowe](https://community.openhab.org/user_avatar/community.openhab.org/andrew_rowe/32/37075_2.png) [@Andrew\_Rowe](https://community.openhab.org/u/Andrew_Rowe)\ **Post date:** [June 8, 2023, 9:52pm UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/22 "2023-06-08T21:52:16Z")
> [@ccutrer](#): > > something in your setup is causing it to get triggered more often. Thanks for reading Cody. For the record, this is a rule that runs every 30 seconds for most the day (from sunrise to sunset) So it executes a lot. But to be fair, the DSL version ran for over two years before I converted the rule to jRuby. The jRuby version was fine until the switch to OH4 and the new jRuby library which is where the error came from. I been meaning to start another thread to ask for help on that. ---
**Author:** ![jimtng](https://community.openhab.org/user_avatar/community.openhab.org/jimtng/32/98543_2.png) [@jimtng](https://community.openhab.org/u/jimtng)\ **Post date:** [June 11, 2023, 3:28am UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/23 "2023-06-11T03:28:35Z")
> [@Andrew\_Rowe](#): > > For the record, this is a rule that runs every 30 seconds for most the day (from sunrise to sunset) So it executes a lot. I have rules that executes a lot more often than every 30 seconds. The frequency shouldn’t be the issue. It sounds like you might need to open a new topic and paste the rule so we can take a look in case it’s something that can be mitigated in the helper library or core. ---
**Author:** ![florian-h05](https://community.openhab.org/user_avatar/community.openhab.org/florian-h05/32/117524_2.png) [@florian-h05](https://community.openhab.org/u/florian-h05)\ **Post date:** [July 30, 2023, 6:37am UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/24 "2023-07-30T06:37:40Z")
Do you still experience that issue today? ---
**Author:** ![Andrew\_Rowe](https://community.openhab.org/user_avatar/community.openhab.org/andrew_rowe/32/37075_2.png) [@Andrew\_Rowe](https://community.openhab.org/u/Andrew_Rowe)\ **Post date:** [July 30, 2023, 11:50am UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/25 "2023-07-30T11:50:41Z")
Florian, are you asking me? If so, yes, I’m still experiencing this issue. (most recently yesterday morning) Running 4.0.0 snapshot 3460. ---
**Author:** ![florian-h05](https://community.openhab.org/user_avatar/community.openhab.org/florian-h05/32/117524_2.png) [@florian-h05](https://community.openhab.org/u/florian-h05)\ **Post date:** [July 30, 2023, 12:08pm UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/26 "2023-07-30T12:08:40Z")
I am more or less asking anyone here, just interested what is the state here. > [@Andrew\_Rowe](#): > > Running 4.0.0 snapshot 3460. That is a really old snapshot, the last 4.0.0 SNAPSHOT was probably 355x, the latest SNAPSHOT is 3570. ---
**Author:** ![Andrew\_Rowe](https://community.openhab.org/user_avatar/community.openhab.org/andrew_rowe/32/37075_2.png) [@Andrew\_Rowe](https://community.openhab.org/u/Andrew_Rowe)\ **Post date:** [July 30, 2023, 12:29pm UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/27 "2023-07-30T12:29:49Z")
> [@florian-h05](#): > > just interested what is the state here I’m still experiencing the issue. I created a script from [Cody’s post above](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/13) and run it occasionaly when the problem occurs and it clears the issue > [@florian-h05](#): > > That is a really old snapshot yeah, sorry, I disabled most my rules and sort of gave up. I figured because no one else was reporting that it was something unique to my set up and have been meaning to start fresh from a clean install but never got around to it. ---
**Author:** ![ccutrer](https://community.openhab.org/user_avatar/community.openhab.org/ccutrer/32/73828_2.png) [@ccutrer](https://community.openhab.org/u/ccutrer)\ **Post date:** [July 30, 2023, 3:17pm UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/28 "2023-07-30T15:17:01Z")
I still see it occasionally. I’m running 4.0.0.M5 on my main instance (I have a handful of addons that I need to polish up PRs on, but in the meantime I rebase, recompile, and reinstall them each time I update openHAB, so it’s not something I do unless I have time to sit down for a bit and get it done). ---
**Author:** ![jmckenna](https://community.openhab.org/user_avatar/community.openhab.org/jmckenna/32/1202_2.png) [@jmckenna](https://community.openhab.org/u/jmckenna)\ **Post date:** [July 30, 2023, 5:51pm UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/29 "2023-07-30T17:51:04Z")
This happens to me as well with latest 4.0 release build using ubuntu’s build of openjdk 17. The thread consuming all the resources seems to always be the “items-queue”. ---
**Author:** ![J-N-K](https://community.openhab.org/user_avatar/community.openhab.org/j-n-k/32/19276_2.png) [@J-N-K](https://community.openhab.org/u/J-N-K)\ **Post date:** [July 30, 2023, 9:11pm UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/30 "2023-07-30T21:11:49Z")
Do you see any messages regarding large queue size in the log? ---
**Author:** ![jmckenna](https://community.openhab.org/user_avatar/community.openhab.org/jmckenna/32/1202_2.png) [@jmckenna](https://community.openhab.org/u/jmckenna)\ **Post date:** [July 31, 2023, 1:46am UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/31 "2023-07-31T01:46:10Z")
No messages regarding large queue size. CPU spikes roughly three times an hour with no specific frequency. I cannot seem to pair it to any events in event log or messages in openhab log. I only noticed the CPU spikes because the CPU fan revs up when it is under load. ![Screenshot 2023-07-30 214024](https://community-openhab-org.s3.dualstack.eu-central-1.amazonaws.com/original/3X/c/d/cdb2ab814d5e930d41e0f9f568deb5f86f5aab48.png) I was thinking of switching to an Azul openjdk build, but I’m not thinking this will make much of a difference. I noticed the jdk bug referenced earlier ([https://bugs.java.com/bugdatabase/view\_bug?bug\_id=8301341](https://bugs.java.com/bugdatabase/view_bug?bug_id=8301341)) has been recently fixed, but it is only on the openjdk 22 master branch right now. ---
**Author:** ![jmckenna](https://community.openhab.org/user_avatar/community.openhab.org/jmckenna/32/1202_2.png) [@jmckenna](https://community.openhab.org/u/jmckenna)\ **Post date:** [August 2, 2023, 2:12am UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/32 "2023-08-02T02:12:29Z")
Here is a snapshot of top and jconsole while spike is occurring. It doesn’t look like it is memory pressure either. ![oh4_cpu_spike](https://community-openhab-org.s3.dualstack.eu-central-1.amazonaws.com/original/3X/8/0/8043b167598ccd32cb0b736167c5957719157ade.png) ---
**Author:** ![MikeJMajor](https://community.openhab.org/user_avatar/community.openhab.org/mikejmajor/32/25283_2.png) [@MikeJMajor](https://community.openhab.org/u/MikeJMajor)\ **Post date:** [August 2, 2023, 6:15am UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/33 "2023-08-02T06:15:15Z")
Same issue with safeCall-queue using 100% on OH 4.0. Nothing in the logs. This is on a RPI3 with: openjdk version “17.0.7” 2023-04-18 OpenJDK Runtime Environment Temurin-17.0.7+7 (build 17.0.7+7) OpenJDK Server VM Temurin-17.0.7+7 (build 17.0.7+7, mixed mode My rules are all UI written in Groovy. ---
**Author:** ![Lolodomo](https://community.openhab.org/letter_avatar_proxy/v4/letter/l/ac91a4/32.png) [@Lolodomo](https://community.openhab.org/u/Lolodomo)\ **Post date:** [August 2, 2023, 7:43am UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/34 "2023-08-02T07:43:16Z")
Are there moments you have massive updates of items? Does it correspond to the spikes? What persistence services are you using? ---
**Author:** ![MikeJMajor](https://community.openhab.org/user_avatar/community.openhab.org/mikejmajor/32/25283_2.png) [@MikeJMajor](https://community.openhab.org/u/MikeJMajor)\ **Post date:** [August 2, 2023, 8:25am UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/35 "2023-08-02T08:25:30Z")
At most I might have about 25 items all updating around the same time. I’m using RRD4j and MapDB persistence. For me its not a spike, safeCall-queue looks to be constantly using 100% cpu for at least the last 3 hours. ---
**Author:** ![Lolodomo](https://community.openhab.org/letter_avatar_proxy/v4/letter/l/ac91a4/32.png) [@Lolodomo](https://community.openhab.org/u/Lolodomo)\ **Post date:** [August 2, 2023, 1:31pm UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/36 "2023-08-02T13:31:54Z")
I am not using MapDB, so maybe it’s worth testing without it. ---
**Author:** ![wborn](https://community.openhab.org/user_avatar/community.openhab.org/wborn/32/55946_2.png) [@wborn](https://community.openhab.org/u/wborn)\ **Post date:** [August 2, 2023, 2:28pm UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/37 "2023-08-02T14:28:06Z")
If a thread is misbehaving, create a thread dump and see what the threads are doing by executing the `threads` command in the [Console](https://www.openhab.org/docs/administration/console.html#the-console). ---
**Author:** ![MikeJMajor](https://community.openhab.org/user_avatar/community.openhab.org/mikejmajor/32/25283_2.png) [@MikeJMajor](https://community.openhab.org/u/MikeJMajor)\ **Post date:** [August 2, 2023, 3:17pm UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/38 "2023-08-02T15:17:44Z")
I ran jstack and it looks stuck the same as the OP ```auto "safeCall-queue" #149807 prio=5 os_prio=0 cpu=11683997.90ms elapsed=11700.68s allocated=136B defined_classes=0 tid=0x4bf55f20 nid=0x5ee1 runnable [0x5995e000] java.lang.Thread.State: RUNNABLE at java.util.concurrent.LinkedTransferQueue.awaitMatch(java.base@17.0.7/LinkedTransferQueue.java:652) at java.util.concurrent.LinkedTransferQueue.xfer(java.base@17.0.7/LinkedTransferQueue.java:616) at java.util.concurrent.LinkedTransferQueue.poll(java.base@17.0.7/LinkedTransferQueue.java:1294) at org.openhab.core.common.QueueingThreadPoolExecutor$1.run(QueueingThreadPoolExecutor.java:193) at java.lang.Thread.run(java.base@17.0.7/Thread.java:833) ``` ---
**Author:** ![ccutrer](https://community.openhab.org/user_avatar/community.openhab.org/ccutrer/32/73828_2.png) [@ccutrer](https://community.openhab.org/u/ccutrer)\ **Post date:** [August 2, 2023, 4:29pm UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/39 "2023-08-02T16:29:45Z")
The 100% CPU issue is when the underlying queue is _empty_ for a thread. It fixes itself when enough items are sent through the higher level queue to necessitate sending one through the lower level queue. ---
**Author:** ![wborn](https://community.openhab.org/user_avatar/community.openhab.org/wborn/32/55946_2.png) [@wborn](https://community.openhab.org/u/wborn)\ **Post date:** [August 6, 2023, 9:03pm UTC](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792/40 "2023-08-06T21:03:07Z")
> [@jmckenna](#): > > but it is only on the openjdk 22 master branch right now I asked for a backport to Java 17 in the PR with the fix. 🤞 > > > This update addresses performance issues across both LinkedTransferQueue and Syn…chronousQueue by creating a common basis for implementation across them (mainly in LinkedTransferQueue). Pasting from internal doc summary of changes: > \* \* Class DualNode replaces Qnode, with fields and methods > \* that apply to any match-based dual data structure, and now > \* usable in other j.u.c classes. in particular, SynchronousQueue. > \* \* Blocking control (in class DualNode) accommodates > \* VirtualThreads and (perhaps virtualized) uniprocessors. > \* \* All fields of this class (LinkedTransferQueue) are > \* default-initializable (to null), allowing further extension > \* (in particular, SynchronousQueue.Transferer) > \* \* Head and tail fields are lazily initialized rather than set > \* to a dummy node, while also reducing retries under heavy > \* contention and misorderings, and relaxing some accesses, > \* requiring accommodation in many places (as well as > \* adjustments in WhiteBox tests). > > > \--------- > \### Progress > \- \[x\] Change must be properly reviewed (1 review required, with at least 1 \[Reviewer\](https://openjdk.org/bylaws#reviewer)) > \- \[x\] Change must not contain extraneous whitespace > \- \[x\] Commit message must refer to an issue > > \### Issues > \* \[JDK-8301341\](https://bugs.openjdk.org/browse/JDK-8301341): LinkedTransferQueue does not respect timeout for poll() (\*\*Bug\*\* - P4) > \* \[JDK-8300663\](https://bugs.openjdk.org/browse/JDK-8300663): java/util/concurrent/SynchronousQueue/Fairness.java failed with "Error: fair=true i=0 j=1" (\*\*Bug\*\* - P3) > \* \[JDK-8267502\](https://bugs.openjdk.org/browse/JDK-8267502): JDK-8246677 caused 16x performance regression in SynchronousQueue (\*\*Bug\*\* - P3) > > > \### Reviewers > \* \[Alan Bateman\](https://openjdk.org/census#alanb) (@AlanBateman - \*\*Reviewer\*\*) ⚠️ Review applies to \[eec7e491\](https://git.openjdk.org/jdk/pull/14317/files/eec7e4915a70d4b8803374794f37abeeeb2e7360) > > > \### Reviewing > \\Using \git\\ > > Checkout this PR locally: \\ > \`$ git fetch https://git.openjdk.org/jdk.git pull/14317/head:pull/14317\` \\ > \`$ git checkout pull/14317\` > > Update a local copy of the PR: \\ > \`$ git checkout pull/14317\` \\ > \`$ git pull https://git.openjdk.org/jdk.git pull/14317/head\` > > \ > \\Using Skara CLI tools\ > > Checkout this PR locally: \\ > \`$ git pr checkout 14317\` > > View PR using the GUI difftool: \\ > \`$ git pr show -t 14317\` > > \ > \\Using diff file\ > > Download this PR as a diff file: \\ > \https://git.openjdk.org/jdk/pull/14317.diff\ > > \ > > > \### Webrev > \[Link to Webrev Comment\](https://git.openjdk.org/jdk/pull/14317#issuecomment-1577305984) [Previous page](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792.md?page=1) [Next page](https://community.openhab.org/t/consistent-100-cpu-use-of-safecall-queue-thread/143792.md?page=3)