James Estes created HBASE-14177:
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Summary: Full GC on client may lead to missing scan results
Key: HBASE-14177
URL: https://issues.apache.org/jira/browse/HBASE-14177
Project: HBase
Issue Type: Bug
Components: Client
Affects Versions: 0.98.13, 0.98.12, 1.1.0
Reporter: James Estes
After adding a large row, scanning back that row winds up being empty. After a
few attempts it will succeed (all attempts over the same data on an hbase
getting no other writes).
Looking at logs, it seems this happens when there is memory pressure on the
client and there are several Full GCs that happen. Then messages that indicate
that region locations are being removed from the local client cache:
2015-07-31 12:50:24,647 [main] DEBUG
org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation -
Removed 192.168.1.131:50981 as a location of
big_row_1438368609944,,1438368610048.880c849594807bdc7412f4f982337d6c. for
tableName=big_row_1438368609944 from cache
Blaming the GC may sound crazy, but if the test is run with -Xms4g -Xmx4g then
it always passes on the first scan attempt. Maybe the pause is enough to remove
something from the cache, or the client is using weak references somewhere?
More info
http://mail-archives.apache.org/mod_mbox/hbase-user/201507.mbox/%3CCAE8tVdnFf%3Dob569%3DfJkpw1ndVWOVTkihYj9eo6qt0FrzihYHgw%40mail.gmail.com%3E
Test used to reproduce:
https://github.com/housejester/hbase-debugging#fullgctest
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