Ruby

TL;DR¶

This issue occurred in Windows version of Fluentd.
It uses ServerEngine and its logger functionality delegates into Ruby logger library.
Fluentd's logrotate functionality is originated from Ruby logger library,
Then, I found that this library does not seems to support logrotate under multi process/thread condition on Windows.

Issue Detail¶

When a log file which is written from the one process or thread, it works correctly:

require "logger"

logger = Logger.new('test.log', 5, 30*1024)

loop do
  logger.error "lost connection"
  logger.debug "got new connection"
end

But logger writing file collision circumstances, it cannot handle logrotate correctly:

require "logger"

logger = Logger.new('test.log', 5, 30*1024)
myOtherLogger = Logger.new('test.log', 5, 30*1024)

loop do
  logger.error "lost connection"
  logger.debug "got new connection"
end

...
log shifting failed. closed stream
log writing failed. closed stream
log shifting failed. closed stream
log writing failed. closed stream
log shifting failed. closed stream
log writing failed. closed stream
log shifting failed. closed stream
log writing failed. closed stream
log shifting failed. closed stream
log writing failed. closed stream
.... (after that many of these lines)

Fluentd launches spawn model (which has supervisor and several workers) on Windows.
Currently, Fluentd implementation uses one logfile from supervisor and worker(s).
So, it causes log shifting operation collision.

Expected behavior¶

Logrorating operation works correctly under multi process/threading circumstances on Windows like as Linux environment.