Chengbing Liu created HDFS-16872:
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Summary: Fix log throttling by declaring LogThrottlingHelper as
static members
Key: HDFS-16872
URL: https://issues.apache.org/jira/browse/HDFS-16872
Project: Hadoop HDFS
Issue Type: Bug
Affects Versions: 3.3.4
Reporter: Chengbing Liu
In our production cluster with Observer NameNode enabled, we have plenty of
logs printed by {{FSEditLogLoader}} and {{RedundantEditLogInputStream}}. The
{{LogThrottlingHelper}} doesn't seem to work.
{noformat}
2022-10-25 09:26:50,380 INFO org.apache.hadoop.hdfs.server.namenode.FSImage:
Start loading edits file ByteStringEditLog[17686250688, 17686250688],
ByteStringEditLog[17686250688, 17686250688], ByteStringEditLog[17686250688,
17686250688] maxTxnsToRead = 9223372036854775807
2022-10-25 09:26:50,380 INFO
org.apache.hadoop.hdfs.server.namenode.RedundantEditLogInputStream:
Fast-forwarding stream 'ByteStringEditLog[17686250688, 17686250688],
ByteStringEditLog[17686250688, 17686250688], ByteStringEditLog[17686250688,
17686250688]' to transaction ID 17686250688
2022-10-25 09:26:50,380 INFO
org.apache.hadoop.hdfs.server.namenode.RedundantEditLogInputStream:
Fast-forwarding stream 'ByteStringEditLog[17686250688, 17686250688]' to
transaction ID 17686250688
2022-10-25 09:26:50,380 INFO org.apache.hadoop.hdfs.server.namenode.FSImage:
Loaded 1 edits file(s) (the last named ByteStringEditLog[17686250688,
17686250688], ByteStringEditLog[17686250688, 17686250688],
ByteStringEditLog[17686250688, 17686250688]) of total size 527.0, total edits
1.0, total load time 0.0 ms
2022-10-25 09:26:50,387 INFO org.apache.hadoop.hdfs.server.namenode.FSImage:
Start loading edits file ByteStringEditLog[17686250689, 17686250693],
ByteStringEditLog[17686250689, 17686250693], ByteStringEditLog[17686250689,
17686250693] maxTxnsToRead = 9223372036854775807
2022-10-25 09:26:50,387 INFO
org.apache.hadoop.hdfs.server.namenode.RedundantEditLogInputStream:
Fast-forwarding stream 'ByteStringEditLog[17686250689, 17686250693],
ByteStringEditLog[17686250689, 17686250693], ByteStringEditLog[17686250689,
17686250693]' to transaction ID 17686250689
2022-10-25 09:26:50,387 INFO
org.apache.hadoop.hdfs.server.namenode.RedundantEditLogInputStream:
Fast-forwarding stream 'ByteStringEditLog[17686250689, 17686250693]' to
transaction ID 17686250689
2022-10-25 09:26:50,387 INFO org.apache.hadoop.hdfs.server.namenode.FSImage:
Loaded 1 edits file(s) (the last named ByteStringEditLog[17686250689,
17686250693], ByteStringEditLog[17686250689, 17686250693],
ByteStringEditLog[17686250689, 17686250693]) of total size 890.0, total edits
5.0, total load time 1.0 ms
{noformat}
After some digging, I found the cause is that {{LogThrottlingHelper}}'s are
declared as instance variables of all the enclosing classes, including
{{FSImage}}, {{FSEditLogLoader}} and {{RedundantEditLogInputStream}}. Therefore
the logging frequency will not be limited across different instances. For
classes with only limited number of instances, such as {{FSImage}}, this is
fine. For others whose instances are created frequently, such as
{{FSEditLogLoader}} and {{RedundantEditLogInputStream}}, it will result in
plenty of logs.
This can be fixed by declaring {{LogThrottlingHelper}}'s as static members.
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