FileCleaningTracker Vector performs badly under load
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Key: IO-220
URL: https://issues.apache.org/jira/browse/IO-220
Project: Commons IO
Issue Type: Bug
Affects Versions: 1.4, 1.3.2, 1.3.1, 1.3, 1.2, 1.1, 1.0, 2.0, 2.x
Environment: Using commons-io-1.4 via commons-fileupload-1.1.1 in
Apache Tomcat/5.5.0 on Java 1.6.
Reporter: Michael Haverkamp
When subjected to heavy load, the performance of
org.apache.commons.io.FileCleaningTracker degrades and becomes a bottleneck to
the system. In our case, we had over 2 millions entries on the "trackers"
Vector. Under these conditions, the call to trackers.remove(tracker) on line
214 becomes very inefficient as it causes the Vector to shift and reindex the
remaining data. In addition, calls to trackers.add are forced to wait on the
inefficient remove operation. With the application idle, it took several hours
for the File Reaper thread to finish processing the entries on the trackers
Vector.
The solution for use was to implement trackers as a HashSet instead of a
Vector. Thus line 52 was changed from:
final Collection /* Tracker */ trackers = new Vector(); // synchronized
to
final Collection /* Tracker */ trackers = Collections.synchronizedSet(new
HashSet()); // synchronized
Imports were also change appropriately.
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