NIcholas Rushton created CASSANDRA-13133:
--------------------------------------------
Summary: Unclosed file descriptors when querying SnapshotsSize
metric
Key: CASSANDRA-13133
URL: https://issues.apache.org/jira/browse/CASSANDRA-13133
Project: Cassandra
Issue Type: Bug
Components: Core
Environment: CentOS 7
Reporter: NIcholas Rushton
Fix For: 3.9
Started to notice many open file descriptors (100k+) per node, growing at a
rate of about 30 per minute in our cluster. After turning off our JMX exporting
server which gets queried every 30 seconds, the number of file descriptors
remained static.
Digging a bit further I ran a jmx dump tool over all the cassandra metrics and
tracked the number of file descriptors after each query, boiling it down to a
single metric causing the number of file descriptors to increase:
org.apache.cassandra.metrics:keyspace=tpsv1,name=SnapshotsSize,scope=events_by_engagement_id,type=Table
running a query a few times against this metric shows the file descriptors
increasing after each query:
{code}
for _ in {0..3}
do
java -jar jmx-dump-0.4.2-standalone.jar --port 7199 --dump
org.apache.cassandra.metrics:keyspace=tpsv1,name=SnapshotsSize,scope=events_by_engagement_id,type=Table
> /dev/null;
sudo lsof -p `pgrep -f CassandraDaemon` | fgrep "DIR" | awk
'{a[$(NF)]+=1}END{for(k in a){print k, a[k]}}' | grep "events_by"
done
> /data/cassandra/data/tpsv1/events_by_engagement_id-01d8f450a54911e6917ec93f8a91ec71
> 33176
> /data/cassandra/data/tpsv1/events_by_engagement_id-01d8f450a54911e6917ec93f8a91ec71
> 33177
> /data/cassandra/data/tpsv1/events_by_engagement_id-01d8f450a54911e6917ec93f8a91ec71
> 33178
> /data/cassandra/data/tpsv1/events_by_engagement_id-01d8f450a54911e6917ec93f8a91ec71
> 33179
{code}
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
