Performance(time) affected because of PR #4429 in LogFileImpl::writeImpl FLUSH. #4429 #2443 code changes due to this has impacted performance.

[chetanshivaji]

Describe the bug
Because of changes of flush time performance is increased #4429 #2443

To Reproduce
Just write multiple logs to file.

Expected behavior
For version 1.13.0 the performance is good. but after introduction of this change in 1.13.1 I see performance hit.
Default flush and fsync is the problem.

@matejk
@sdaly2107

[chetanshivaji]

I changed nothing from my code,
but simply upgrading poco to latest version 1.13.3, there is substantial time performance impact.
When I reverted version to 1.13.0 poco, I get older good performance.
So there is performance issue due to this code change of file write, flush, fsync.
Please have a look.

[matejk]

Which OS do you use?

Do you use flush option for logging?

[chetanshivaji]

Mine is container application, I have my application on top of Oracle Linux as base image.
Any OS, I do docker run it should show performance issue.
I tried running on Ubuntu, and Oracle OEL.

[matejk]

Semantics if flush option for logging was unified across platforms. It means immediate sync to disk for every write on all platforms now.

If you want high performance then don't use flush option.

[chetanshivaji]

We dont change flush option, but use by default offered by POCO. I believe by default it is TRUE from poco.
I will override flush to false. and I will try for performance.
Thank you. @matejk

[matejk]

@chetanshivaji, do you use Poco::SimpleFileChannel or Poco::FileChannel?

[chetanshivaji]

@matejk
I use, I did use below flush =false, to get back to older good performance.

logging.channels.c3.class = FileChannel
logging.channels.c3.purgeCount = 5
logging.channels.c3.flush = false

[matejk]

@aleks-f , does "flush" setting in channel configuration default to "true" is it is not defined by any chance in some cases?