You are viewing a plain text version of this content. The canonical link for it is here.
Posted to reviews@spark.apache.org by "pan3793 (via GitHub)" <gi...@apache.org> on 2026/03/20 11:39:16 UTC
[PR] [SPARK-55809][CORE] HeapHistogram uses DiagnosticCommandMBean instead of jmap subprocess [spark]
pan3793 opened a new pull request, #54919:
URL: https://github.com/apache/spark/pull/54919
<!--
Thanks for sending a pull request! Here are some tips for you:
1. If this is your first time, please read our contributor guidelines: https://spark.apache.org/contributing.html
2. Ensure you have added or run the appropriate tests for your PR: https://spark.apache.org/developer-tools.html
3. If the PR is unfinished, add '[WIP]' in your PR title, e.g., '[WIP][SPARK-XXXX] Your PR title ...'.
4. Be sure to keep the PR description updated to reflect all changes.
5. Please write your PR title to summarize what this PR proposes.
6. If possible, provide a concise example to reproduce the issue for a faster review.
7. If you want to add a new configuration, please read the guideline first for naming configurations in
'core/src/main/scala/org/apache/spark/internal/config/ConfigEntry.scala'.
8. If you want to add or modify an error type or message, please read the guideline first in
'common/utils/src/main/resources/error/README.md'.
-->
### What changes were proposed in this pull request?
<!--
Please clarify what changes you are proposing. The purpose of this section is to outline the changes and how this PR fixes the issue.
If possible, please consider writing useful notes for better and faster reviews in your PR. See the examples below.
1. If you refactor some codes with changing classes, showing the class hierarchy will help reviewers.
2. If you fix some SQL features, you can provide some references of other DBMSes.
3. If there is design documentation, please add the link.
4. If there is a discussion in the mailing list, please add the link.
-->
Re-implement `Utils.getHeapHistogram` to use `DiagnosticCommandMBean` in-process instead of spawning `jmap` as a subprocess.
### Why are the changes needed?
<!--
Please clarify why the changes are needed. For instance,
1. If you propose a new API, clarify the use case for a new API.
2. If you fix a bug, you can clarify why it is a bug.
-->
I found Heap Histogram might cause a hang in JDK 25. The reproduction steps:
1. Run `spark-shell` or `spark-sql` CLI
2. Access the UI Executors tab, and click "Heap Histogram" of the driver
3. Both UI and CLI are stuck
4. Try to run `jstack <pid>`, also stuck
5. Switching to ZGC does not help.
Explanation from Claude:
> Spawning `jmap -histo <pid>` requires a self-attach via signal/socket handshake.
> Any concurrent GC (G1, ZGC, Shenandoah) can put the JVM into states where the
> Signal Dispatcher cannot service the attachment handshake, causing jmap to hang.
> DiagnosticCommandMBean runs gcClassHistogram in-process and coordinates with GC
> through internal JVM APIs, avoiding the unreliable inter-process attach.
### Does this PR introduce _any_ user-facing change?
<!--
Note that it means *any* user-facing change including all aspects such as new features, bug fixes, or other behavior changes. Documentation-only updates are not considered user-facing changes.
If yes, please clarify the previous behavior and the change this PR proposes - provide the console output, description and/or an example to show the behavior difference if possible.
If possible, please also clarify if this is a user-facing change compared to the released Spark versions or within the unreleased branches such as master.
If no, write 'No'.
-->
No.
### How was this patch tested?
<!--
If tests were added, say they were added here. Please make sure to add some test cases that check the changes thoroughly including negative and positive cases if possible.
If it was tested in a way different from regular unit tests, please clarify how you tested step by step, ideally copy and paste-able, so that other reviewers can test and check, and descendants can verify in the future.
If tests were not added, please describe why they were not added and/or why it was difficult to add.
If benchmark tests were added, please run the benchmarks in GitHub Actions for the consistent environment, and the instructions could accord to: https://spark.apache.org/developer-tools.html#github-workflow-benchmarks.
-->
Tested with JDK 17, 25, works as expected
<img width="1728" height="1027" alt="image" src="https://github.com/user-attachments/assets/b2263bbf-60f0-4b89-8d8f-29fd48b26b57" />
### Was this patch authored or co-authored using generative AI tooling?
<!--
If generative AI tooling has been used in the process of authoring this patch, please include the
phrase: 'Generated-by: ' followed by the name of the tool and its version.
If no, write 'No'.
Please refer to the [ASF Generative Tooling Guidance](https://www.apache.org/legal/generative-tooling.html) for details.
-->
Generated-by: Claude Code.
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For queries about this service, please contact Infrastructure at:
users@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org
Re: [PR] [SPARK-55809][CORE] HeapHistogram uses DiagnosticCommandMBean instead of jmap subprocess [spark]
Posted by "dongjoon-hyun (via GitHub)" <gi...@apache.org>.
dongjoon-hyun closed pull request #54919: [SPARK-55809][CORE] HeapHistogram uses DiagnosticCommandMBean instead of jmap subprocess
URL: https://github.com/apache/spark/pull/54919
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For queries about this service, please contact Infrastructure at:
users@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org
Re: [PR] [SPARK-55809][CORE] HeapHistogram uses DiagnosticCommandMBean instead of jmap subprocess [spark]
Posted by "pan3793 (via GitHub)" <gi...@apache.org>.
pan3793 commented on PR #54919:
URL: https://github.com/apache/spark/pull/54919#issuecomment-4097563044
cc @dongjoon-hyun @mridulm @cxzl25
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For queries about this service, please contact Infrastructure at:
users@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org
Re: [PR] [SPARK-55809][CORE] HeapHistogram uses DiagnosticCommandMBean instead of jmap subprocess [spark]
Posted by "cxzl25 (via GitHub)" <gi...@apache.org>.
cxzl25 commented on code in PR #54919:
URL: https://github.com/apache/spark/pull/54919#discussion_r2973620249
##########
core/src/main/scala/org/apache/spark/util/Utils.scala:
##########
@@ -2144,19 +2145,18 @@ private[spark] object Utils
/** Return a heap dump. Used to capture dumps for the web UI */
def getHeapHistogram(): Array[String] = {
- val pid = String.valueOf(ProcessHandle.current().pid())
- val jmap = System.getProperty("java.home") + "/bin/jmap"
- val builder = new ProcessBuilder(jmap, "-histo:live", pid)
Review Comment:
### Root cause
The reason is that JDK25 8354460 changes the output of jmap to streaming output. If it is not read in time, this will cause the buffer to be exhausted and the process will appear to hang.
https://bugs.openjdk.org/browse/JDK-8354460
### Test
The way using MBean looks better, the following is just my verification test.
With the `-J-Djdk.attach.allowStreamingOutput=false` parameter, Spark generates HeapHistogram normally.
```scala
val builder = new ProcessBuilder(jmap, "-J-Djdk.attach.allowStreamingOutput=false", "-histo:live", pid)
```
### Related
JVM freezes when executing a jmap command using the Process and Runtime API
https://bugs.openjdk.org/browse/JDK-8372842
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For queries about this service, please contact Infrastructure at:
users@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org
Re: [PR] [SPARK-55809][CORE] HeapHistogram uses DiagnosticCommandMBean instead of jmap subprocess [spark]
Posted by "dongjoon-hyun (via GitHub)" <gi...@apache.org>.
dongjoon-hyun commented on PR #54919:
URL: https://github.com/apache/spark/pull/54919#issuecomment-4098001057
I also verified manually with JDK 25.
<img width="849" height="352" alt="Screenshot 2026-03-20 at 06 32 41" src="https://github.com/user-attachments/assets/13678e13-787d-4f4a-a39d-d7a1c2df59a0" />
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For queries about this service, please contact Infrastructure at:
users@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org
Re: [PR] [SPARK-55809][CORE] HeapHistogram uses DiagnosticCommandMBean instead of jmap subprocess [spark]
Posted by "pan3793 (via GitHub)" <gi...@apache.org>.
pan3793 commented on code in PR #54919:
URL: https://github.com/apache/spark/pull/54919#discussion_r2973661106
##########
core/src/main/scala/org/apache/spark/util/Utils.scala:
##########
@@ -2144,19 +2145,18 @@ private[spark] object Utils
/** Return a heap dump. Used to capture dumps for the web UI */
def getHeapHistogram(): Array[String] = {
- val pid = String.valueOf(ProcessHandle.current().pid())
- val jmap = System.getProperty("java.home") + "/bin/jmap"
- val builder = new ProcessBuilder(jmap, "-histo:live", pid)
Review Comment:
@cxzl25, thanks for finding out the root cause! so the comment is not correct, would you like to send a follow-up PR to fix the comment?
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For queries about this service, please contact Infrastructure at:
users@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org
Re: [PR] [SPARK-55809][CORE] HeapHistogram uses DiagnosticCommandMBean instead of jmap subprocess [spark]
Posted by "dongjoon-hyun (via GitHub)" <gi...@apache.org>.
dongjoon-hyun commented on code in PR #54919:
URL: https://github.com/apache/spark/pull/54919#discussion_r2975955933
##########
core/src/main/scala/org/apache/spark/util/Utils.scala:
##########
@@ -2144,19 +2145,18 @@ private[spark] object Utils
/** Return a heap dump. Used to capture dumps for the web UI */
def getHeapHistogram(): Array[String] = {
- val pid = String.valueOf(ProcessHandle.current().pid())
- val jmap = System.getProperty("java.home") + "/bin/jmap"
- val builder = new ProcessBuilder(jmap, "-histo:live", pid)
Review Comment:
Nice analysis!
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For queries about this service, please contact Infrastructure at:
users@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org
Re: [PR] [SPARK-55809][CORE] HeapHistogram uses DiagnosticCommandMBean instead of jmap subprocess [spark]
Posted by "dongjoon-hyun (via GitHub)" <gi...@apache.org>.
dongjoon-hyun commented on PR #54919:
URL: https://github.com/apache/spark/pull/54919#issuecomment-4098005385
Merged to master for Apache Spark 4.2.0.
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For queries about this service, please contact Infrastructure at:
users@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org
Re: [PR] [SPARK-55809][CORE] HeapHistogram uses DiagnosticCommandMBean instead of jmap subprocess [spark]
Posted by "pan3793 (via GitHub)" <gi...@apache.org>.
pan3793 commented on PR #54919:
URL: https://github.com/apache/spark/pull/54919#issuecomment-4097445012
Additionally, I tested the new proposed approach by porting it to the internal Spark 3 version, it also works on Java 8.
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For queries about this service, please contact Infrastructure at:
users@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org