Jörg Schaible schrieb:
Jean-Philippe Daigle wrote:
[snip]
Ah, so there's one more thing I hadn't tried, which I just did, and
explained a bit of the situation: completely removing the
logging block
(don't check isDebugEnabled(), don't call .debug(), etc.
Removing the whole logging block results in getting the same slow
throughput case that I was blaming on isDebugEnabled().
Replacing it with just this assignment (to a public var so it's not
optimized away):
_dbg_str = String.format("appack>>> id=%s res=%s", id, ack_r);
Gives me the fast throughput case. Wow. So apache commons logging is
blameless, what determines whether you get the fast or the
slow message
throughput case is actually _slowing down the thread calling the
ackMessage() method_. Slowing down this frequently-called method with
useless String.format() work results in more than double the
throughput.
I have no idea why (it's counterintuitive), I suspect I need
to get more
visibility into the interactions between threads here.
Thanks to everyone that read this thread, looks like the problem's
somewhere else in my code. (Though if you DO have any suggestions that
could explain what I'm seeing, let me know, even if this is
no longer a
logging issue :) )
Can you stip it down to detect the real call that is responsible for the
speed-up?
1/ _dbg_str = ack_r.toString();
or
2/ _dbg_str = String.valueOf(id);
or even
3/ ack_r.toString();
alone?
What's implemented with ack_r.toString() ? What kind of implementation is ack_r
? A proxy ?
Yes, good point. I missed that ack_r.toString will be triggered.
I wonder what happens if you replace the String.format call with just this:
synchronized(this) {
++dummy;
}
where dummy is a public int member, just so the synchronized block isn't
optimised away. The synchronization operation will have a number of
side-effects, including entering the OS kernel, flushing CPU caches and
allowing the OS scheduler to run.
Regards,
Simon
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