Haruki Okada created KAFKA-13403:
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Summary: KafkaServer crashes when deleting topics due to the race
in log deletion
Key: KAFKA-13403
URL: https://issues.apache.org/jira/browse/KAFKA-13403
Project: Kafka
Issue Type: Bug
Components: core
Affects Versions: 2.4.1
Reporter: Haruki Okada
h2. Environment
* OS: CentOS Linux release 7.6
* Kafka version: 2.4.1
** But as far as I checked the code, I think same phenomenon could happen even
on trunk
* Kafka log directory: RAID1+0 (i.e. not using JBOD so only single log.dirs is
set)
* Java version: AdoptOpenJDK 1.8.0_282
h2. Phenomenon
When we were in the middle of deleting several topics by `kafka-topics.sh
--delete --topic blah-blah`, one broker in our cluster crashed due to following
exception:
{code:java}
[2021-10-21 18:19:19,122] ERROR Shutdown broker because all log dirs in
/data/kafka have failed (kafka.log.LogManager)
{code}
We also found NoSuchFileException was thrown right before the crash when
LogManager tried to delete logs for some partitions.
{code:java}
[2021-10-21 18:19:18,849] ERROR Error while deleting log for foo-bar-topic-5 in
dir /data/kafka (kafka.server.LogDirFailureChannel)
java.nio.file.NoSuchFileException:
/data/kafka/foo-bar-topic-5.df3626d2d9eb41a2aeb0b8d55d7942bd-delete/00000000000003877066.timeindex.deleted
at
sun.nio.fs.UnixException.translateToIOException(UnixException.java:86)
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:102)
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:107)
at
sun.nio.fs.UnixFileAttributeViews$Basic.readAttributes(UnixFileAttributeViews.java:55)
at
sun.nio.fs.UnixFileSystemProvider.readAttributes(UnixFileSystemProvider.java:144)
at
sun.nio.fs.LinuxFileSystemProvider.readAttributes(LinuxFileSystemProvider.java:99)
at java.nio.file.Files.readAttributes(Files.java:1737)
at java.nio.file.FileTreeWalker.getAttributes(FileTreeWalker.java:219)
at java.nio.file.FileTreeWalker.visit(FileTreeWalker.java:276)
at java.nio.file.FileTreeWalker.next(FileTreeWalker.java:372)
at java.nio.file.Files.walkFileTree(Files.java:2706)
at java.nio.file.Files.walkFileTree(Files.java:2742)
at org.apache.kafka.common.utils.Utils.delete(Utils.java:732)
at kafka.log.Log.$anonfun$delete$2(Log.scala:2036)
at
scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
at kafka.log.Log.maybeHandleIOException(Log.scala:2343)
at kafka.log.Log.delete(Log.scala:2030)
at kafka.log.LogManager.deleteLogs(LogManager.scala:826)
at kafka.log.LogManager.$anonfun$deleteLogs$6(LogManager.scala:840)
at
kafka.utils.KafkaScheduler.$anonfun$schedule$2(KafkaScheduler.scala:116)
at kafka.utils.CoreUtils$$anon$1.run(CoreUtils.scala:65)
at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
{code}
So, the log-dir was marked as offline and ended up with KafkaServer crash
because the broker has only single log-dir.
h2. Cause
We also found below logs right before the NoSuchFileException.
{code:java}
[2021-10-21 18:18:17,829] INFO Log for partition foo-bar-5 is renamed to
/data/kafka/foo-bar-5.df3626d2d9eb41a2aeb0b8d55d7942bd-delete and is scheduled
for deletion (kafka.log.LogManager)
[2021-10-21 18:18:17,900] INFO [Log partition=foo-bar-5, dir=/data/kafka] Found
deletable segments with base offsets [3877066] due to retention time
172800000ms breach (kafka.log.Log)[2021-10-21 18:18:17,901] INFO [Log
partition=foo-bar-5, dir=/data/kafka] Scheduling segments for deletion
List(LogSegment(baseOffset=3877066, size=90316366,
lastModifiedTime=1634634956000, largestTime=1634634955854)) (kafka.log.Log)
{code}
After checking through Kafka code, we concluded that there was a race between
"kafka-log-retention" and "kafka-delete-logs" scheduler threads.
Detailed timeline was like below:
- Precondition: there was two log segments (3877066, 4271262) for the partition
foo-bar-5
||time||thread||event||files under partition dir||
|2021-10-21 18:18:17,901|kafka-log-retention|Scheduled deletion for segment
3877066 due to retention|3877066, 4271262|
|2021-10-21 18:19:17,830|kafka-delete-logs|Starting to execute Log.delete()
(which was scheduled by topic deletion)
Deleted all log segments
([https://github.com/apache/kafka/blob/2.4.1/core/src/main/scala/kafka/log/Log.scala#L2031])
However, in the meantim, 3877066 was scheduled for deletion due to retention
and already removed from segment-list, 3877066 was not listed up as deletion
target here.|3877066|
|2021-10-21 18:19:17,830 + X|kafka-delete-logs|Start deleting entire partition
directory by calling Utils.delete()
([https://github.com/apache/kafka/blob/2.4.1/clients/src/main/java/org/apache/kafka/common/utils/Utils.java#L729])
Files.walkFileTree starts to walk inside the directory, and found
3877066|3877066|
|2021-10-21 18:19:17,830 + X|kafka-log-retention|Delete segment 3877066 as
scheduled|empty|
|2021-10-21 18:19:18,849|kafka-delete-logs|Files.walkFileTree tried to read
attributes of 3877066 but it failed with NoSuchFileException|empty|
h2. Suggested solution
* I would like to suggest to fix Utils.delete to swallow NoSuchFileException
and just returns FileVisitResult.CONTINUE here
**
[https://github.com/apache/kafka/blob/2.4.1/clients/src/main/java/org/apache/kafka/common/utils/Utils.java#L736]
* Also, we should use Files.deleteIfExists here
**
[https://github.com/apache/kafka/blob/2.4.1/clients/src/main/java/org/apache/kafka/common/utils/Utils.java#L743]
** Though it was not the case for our situation, this could lead
NoSuchFileException too because the file might be deleted by another thread by
same flow.
* What Utils.delete does is just deleting children recursively,
NoSuchFileException just means we don't have to delete it, so ignoring it and
continuing should be safe.
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