Bruno Iljazovic created KAFKA-9603:
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Summary: Number of open files keeps increasing in Streams
application
Key: KAFKA-9603
URL: https://issues.apache.org/jira/browse/KAFKA-9603
Project: Kafka
Issue Type: Bug
Components: streams
Affects Versions: 2.3.1, 2.4.0
Environment: Spring Boot 2.2.4, OpenJDK 13, Centos image
Reporter: Bruno Iljazovic
Problem appeared when upgrading from *2.0.1* to *2.3.1*.
Relevant Kafka Streams code:
{code:java}
KStream<String, Event1> events1 =
builder.stream(FIRST_TOPIC_NAME, Consumed.with(stringSerde, event1Serde,
event1TimestampExtractor(), null))
.mapValues(...);
KStream<String, Event2> events2 =
builder.stream(SECOND_TOPIC_NAME, Consumed.with(stringSerde, event2Serde,
event2TimestampExtractor(), null))
.mapValues(...);
var joinWindows = JoinWindows.of(Duration.of(1, MINUTES).toMillis())
.until(Duration.of(1, HOURS).toMillis());
events2.join(events1, this::join, joinWindows, Joined.with(stringSerde,
event2Serde, event1Serde))
.foreach(...);
{code}
Number of open *.sst files keeps increasing until eventually it hits the os
limit (65536) and causes this exception:
{code:java}
Caused by: org.rocksdb.RocksDBException: While open a file for appending:
/.../0_8/KSTREAM-JOINOTHER-0000000010-store/KSTREAM-JOINOTHER-0000000010-store.1579435200000/001354.sst:
Too many open files
at org.rocksdb.RocksDB.flush(Native Method)
at org.rocksdb.RocksDB.flush(RocksDB.java:2394)
{code}
Here are example files that are opened and never closed:
{code:java}
/.../0_27/KSTREAM-JOINTHIS-0000000009-store/KSTREAM-JOINTHIS-0000000009-store.1582459200000/000114.sst
/.../0_27/KSTREAM-JOINOTHER-0000000010-store/KSTREAM-JOINOTHER-0000000010-store.1582459200000/000065.sst
/.../0_29/KSTREAM-JOINTHIS-0000000009-store/KSTREAM-JOINTHIS-0000000009-store.1582156800000/000115.sst
/.../0_29/KSTREAM-JOINTHIS-0000000009-store/KSTREAM-JOINTHIS-0000000009-store.1582459200000/000112.sst
/.../0_31/KSTREAM-JOINTHIS-0000000009-store/KSTREAM-JOINTHIS-0000000009-store.1581854400000/000051.sst
{code}
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