Takanori Takase created LOGBACK-1517:
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Summary: Reduce disk io when rolling between different filesystems
Key: LOGBACK-1517
URL: https://jira.qos.ch/browse/LOGBACK-1517
Project: logback
Issue Type: Improvement
Components: logback-core
Affects Versions: 1.2.3
Reporter: Takanori Takase
Assignee: Logback dev list
In "TimeBasedRollingPolicy#renameRawAndAsyncCompress", the temporary file
("*.tmp") is created based on the compressed file path.
{code:java}
Future<?> renameRawAndAsyncCompress(String nameOfCompressedFile, String
innerEntryName) throws RolloverFailure {
String parentsRawFile = getParentsRawFileProperty();
String tmpTarget = nameOfCompressedFile + System.nanoTime() + ".tmp";
renameUtil.rename(parentsRawFile, tmpTarget);
return compressor.asyncCompress(tmpTarget, nameOfCompressedFile,
innerEntryName);
}
{code}
If the active log path and the compressed log path are located in different
filesystems, this could add extra load to the infrastructure especially in
cases where the active log path is under a fast disk (cf: locally-mounted SSDs,
tmpfs) and the compressed log path is under a slower disk (cf: NFS, FUSE).
{noformat}
/fast-disk/logs/example.log
/slow-disk/logs/example.log.gz.nano.tmp
/slow-disk/logs/example.log.gz
{noformat}
The rename writes a temp file into the slow-disk, then reads from the slow disk
for in-memory compression. Both of these require accessing the slow-disk.
This can be optimized by creating the temp file under the same directory as the
active file (assuming that rename doesn't require as much disk io as copying).
{noformat}
/fast-disk/logs/example.log
/fast-disk/logs/example.log.nano.tmp
/slow-disk/logs/example.log.gz
{noformat}
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