Xiangdong Huang created IOTDB-510:
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Summary: A NullPointException in the TsFileProcessor when flushing
memtables
Key: IOTDB-510
URL: https://issues.apache.org/jira/browse/IOTDB-510
Project: Apache IoTDB
Issue Type: Bug
Components: Core/Engine
Affects Versions: 0.10.0-SNAPSHOT
Reporter: Xiangdong Huang
Sometimes when we run TravicCI, the TsFileProcessorTest will hang up.
If we add log in TsFileProcessor, we can find logs like:
WARN [2020-02-22 02:45:54,092] [main]
org.apache.iotdb.db.engine.storagegroup.TsFileProcessor:289 -
C:\Users\travis\build\jixuan1989\incubator-iotdb\server\target\data\testUnsealedTsFileProcessor.tsfile
has spent 60s for waiting flushing one memtable; 1 left (first:
org.apache.iotdb.db.engine.flush.NotifyFlushMemTable@29c53c4f). FlushingManager
info: TSProcessors in the queue: 0, TaskPool size 0 + 0,
WARN [2020-02-22 02:46:54,095] [main]
org.apache.iotdb.db.engine.storagegroup.TsFileProcessor:289 -
C:\Users\travis\build\jixuan1989\incubator-iotdb\server\target\data\testUnsealedTsFileProcessor.tsfile
has spent 120s for waiting flushing one memtable; 1 left (first:
org.apache.iotdb.db.engine.flush.NotifyFlushMemTable@29c53c4f). FlushingManager
info: TSProcessors in the queue: 0, TaskPool size 0 + 0,
WARN [2020-02-22 02:47:54,108] [main]
org.apache.iotdb.db.engine.storagegroup.TsFileProcessor:289 -
C:\Users\travis\build\jixuan1989\incubator-iotdb\server\target\data\testUnsealedTsFileProcessor.tsfile
has spent 180s for waiting flushing one memtable; 1 left (first:
org.apache.iotdb.db.engine.flush.NotifyFlushMemTable@29c53c4f). FlushingManager
info: TSProcessors in the queue: 0, TaskPool size 0 + 0,
WARN [2020-02-22 02:48:54,122] [main]
org.apache.iotdb.db.engine.storagegroup.TsFileProcessor:289 -
C:\Users\travis\build\jixuan1989\incubator-iotdb\server\target\data\testUnsealedTsFileProcessor.tsfile
has spent 240s for waiting flushing one memtable; 1 left (first:
org.apache.iotdb.db.engine.flush.NotifyFlushMemTable@29c53c4f). FlushingManager
info: TSProcessors in the queue: 0, TaskPool size 0 + 0,
WARN [2020-02-22 02:49:54,132] [main]
org.apache.iotdb.db.engine.storagegroup.TsFileProcessor:289 -
C:\Users\travis\build\jixuan1989\incubator-iotdb\server\target\data\testUnsealedTsFileProcessor.tsfile
has spent 300s for waiting flushing one memtable; 1 left (first:
org.apache.iotdb.db.engine.flush.NotifyFlushMemTable@29c53c4f). FlushingManager
info: TSProcessors in the queue: 0, TaskPool size 0 + 0,
WARN [2020-02-22 02:50:54,099] [main]
org.apache.iotdb.db.engine.storagegroup.TsFileProcessor:289 -
C:\Users\travis\build\jixuan1989\incubator-iotdb\server\target\data\testUnsealedTsFileProcessor.tsfile
has spent 360s for waiting flushing one memtable; 1 left (first:
org.apache.iotdb.db.engine.flush.NotifyFlushMemTable@29c53c4f). FlushingManager
info: TSProcessors in the queue: 0, TaskPool size 0 + 0,
Actually it is caused by a nullpointException but we omit the exception in the
releaseFlushedMemTable() method...
The NullPointException happens when:
# A: there is an async flushing task;
# B: users call TsFileProcessor.syncClose;
The process is:
# B set `shouldClose = true` and has not put the final memtable (maybe a
signalMemtable) into the flushingMemtable in asyncClose() (which is called by
syncClose()).
# A checks the `shouldeClose == true && flushingMemtables.isEmpty() ` in
flushOneMemtable(), then A call endFile() to close the fileWriter;
# B then put the final memtable into the flushingMemtable. When begin to flush
the memtable, nullPointException is thrown (because the file Writer was set to
null in endFile()).
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