It looks like there is a race condition between the settings for the 2
properties: log.default.flush.scheduler.interval.ms &
log.default.flush.interval.ms. I'm using 0.7.2.
By default, both of these get set to 3000ms (and in the docs, it
recommends setting flushInterval to be a multiple of the
flushSchedulerInterval).
However, the code in LogManager.flushAllLogs (which is scheduled to
run at a fixed rate using the flushSchedulerInterval property) looks
like this:
val timeSinceLastFlush = System.currentTimeMillis -
log.getLastFlushedTime
var logFlushInterval = config.defaultFlushIntervalMs
....
....
if(timeSinceLastFlush >= logFlushInterval)
log.flush
So, it will only flush logs if the the time since the last flush is
longer than the flush interval. But, the log.lastFlushedTime is not
set until after flushing is completed (which can incur some io time).
Thus, by enabling TRACE logging for this method, I was able to see
that with the defaults, timeSinceLastFlush was usually about 2998
(which is less than the logFlushInterval of 3000). Thus, setting a
flushInterval the same as the scheduler.flushInterval essentially
devolves to an effective flushInterval = 2X the
schedulerFlushInterval.
So, setting a flushIinterval slightly less than the
flushSchedulerInterval (e.g. 2500) will guarantee that the flush will
happen on each scheduler invocation.
I'm guessing that it might make sense to change the logic gating the
flush to something like:
if(timeSinceLastFlush >= 0.90 * logFlushInterval)
might be reasonable. Also, the scheduler probably ought to use a
'fixedDelay' rather than a 'fixedRate' schedule.....
Jason
