HBASE-27563 ChaosMonkey sometimes generates invalid boundaries for random item selection #4954
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This comment was marked as outdated.
This comment was marked as outdated.
This comment was marked as outdated.
This comment was marked as outdated.
This comment was marked as outdated.
This comment was marked as outdated.
Apache9
reviewed
Jan 11, 2023
|
|
||
| int startIndex = ThreadLocalRandom.current().nextInt(items.length - selectedNumber); | ||
| return originalItems.subList(startIndex, startIndex + selectedNumber); | ||
| final int startIndex = |
There was a problem hiding this comment.
So the problem here is ratio could be greater than 1.0?
There was a problem hiding this comment.
Yes, it seems so... and it looks like this patch is not sufficient. Here's the stack trace from branch-2.5.
2023-01-10T19:33:35,651 WARN [ChaosMonkey-0] policies.Policy: Exception occurred during performing action: java.lang.IllegalArgumentException: bound must be positive
at java.base/java.util.Random.nextInt(Random.java:322)
at java.base/java.util.concurrent.ThreadLocalRandom.nextInt(ThreadLocalRandom.java:449)
at org.apache.hadoop.hbase.chaos.monkies.PolicyBasedChaosMonkey.selectRandomItems(PolicyBasedChaosMonkey.java:123)
at org.apache.hadoop.hbase.chaos.actions.RollingBatchRestartRsAction.selectServers(RollingBatchRestartRsAction.java:130)
at org.apache.hadoop.hbase.chaos.actions.RollingBatchRestartRsAction.perform(RollingBatchRestartRsAction.java:75)
at org.apache.hadoop.hbase.chaos.policies.DoActionsOncePolicy.runOneIteration(DoActionsOncePolicy.java:48)
at org.apache.hadoop.hbase.chaos.policies.PeriodicPolicy.run(PeriodicPolicy.java:41)
at org.apache.hadoop.hbase.chaos.policies.CompositeSequentialPolicy.run(CompositeSequentialPolicy.java:42)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:833)
There was a problem hiding this comment.
I think it's more likely that I have ratio == length, we'll have this problem... Let me add some debugging and see what I can learn.
There was a problem hiding this comment.
I think we'd better add some comments here to say why we need these guards? Is it because of the floating point precision?
|
Checked the code, the ratio is percentage of regionservers we want to restart, normally, so in general it should be a value between 0 and 1. But there is no sanity check in our code... |
|
|
We have |
|
This code handles the |
This comment was marked as outdated.
This comment was marked as outdated.
This comment was marked as outdated.
This comment was marked as outdated.
This comment was marked as outdated.
This comment was marked as outdated.
Apache9
reviewed
Jan 12, 2023
|
|
||
| List<T> originalItems = Arrays.asList(items); | ||
| final int selectedNumber = (int) Math.ceil(items.length * ratio); | ||
| final List<T> originalItems = Arrays.asList(items); |
There was a problem hiding this comment.
Arrays.asList will create a ArrayList which is backed by the given array, so the later shuffle will change the order of the items array which is passed in as a parameter. If we think this is acceptable, we can just shuffle on the given array instead of wrapping it? If not, I think we should copy the array.
|
|
||
| int startIndex = ThreadLocalRandom.current().nextInt(items.length - selectedNumber); | ||
| return originalItems.subList(startIndex, startIndex + selectedNumber); | ||
| if (selectedNumber == items.length) { |
|
|
||
| int startIndex = ThreadLocalRandom.current().nextInt(items.length - selectedNumber); | ||
| return originalItems.subList(startIndex, startIndex + selectedNumber); | ||
| final int startIndex = |
There was a problem hiding this comment.
I think we'd better add some comments here to say why we need these guards? Is it because of the floating point precision?
|
Good points all around, thanks @Apache9 |
ndimiduk
commented
Jan 12, 2023
| @@ -151,7 +157,9 @@ public boolean isStopped() { | |||
|
|
|||
| @Override | |||
| public void waitForStop() throws InterruptedException { | |||
| monkeyThreadPool.awaitTermination(1, TimeUnit.MINUTES); | |||
| if (!monkeyThreadPool.awaitTermination(1, TimeUnit.MINUTES)) { | |||
| LOG.warn("Some pool threads failed to terminate, {}", monkeyThreadPool); | |||
There was a problem hiding this comment.
Strange. monkeyThreadPool is not a daemon pool, so if this termination fails for some reason, the process can hang. Let me add a forced shutdown.
This comment was marked as outdated.
This comment was marked as outdated.
This comment was marked as outdated.
This comment was marked as outdated.
This comment was marked as outdated.
This comment was marked as outdated.
Apache9
approved these changes
Jan 12, 2023
Apache9
reviewed
Jan 12, 2023
| final int startIndex = | ||
| Math.max(0, ThreadLocalRandom.current().nextInt(items.length - selectedNumber)); | ||
| final int endIndex = Math.min(items.length, startIndex + selectedNumber); | ||
| return shuffledItems.subList(startIndex, endIndex); |
There was a problem hiding this comment.
Maybe here you could make use of org.apache.hadoop.hbase.util.ReservoirSample so we do not need to copy the whole array? Not a blocker issue anyway.
ndimiduk
force-pushed
the
27563-chaosmonkey-invalid-boundaries
branch
from
5ea901a to
00ca430
Compare
…ndom item selection Signed-off-by: Duo Zhang <zhangduo@apache.org>
ndimiduk
force-pushed
the
27563-chaosmonkey-invalid-boundaries
branch
from
00ca430 to
b02e312
Compare
|
🎊 +1 overall
This message was automatically generated. |
|
🎊 +1 overall
This message was automatically generated. |
|
🎊 +1 overall
This message was automatically generated. |
|
🎊 +1 overall
This message was automatically generated. |
|
🎊 +1 overall
This message was automatically generated. |
|
🎊 +1 overall
This message was automatically generated. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Clamp the boundaries of the selected sublist according to the input list size.