Buffered Logging?

[Ramki Ramakrishna]

I filed https://bugs.openjdk.java.net/browse/JDK-8229517.  Please
correct/complete if I mangled or neglected to fill any specific required
fields.

Patches forthcoming in the next few days.
-- ramki

On Tue, Aug 13, 2019 at 2:53 PM Ramki Ramakrishna <rramakrishna at twitter.com>
wrote:

>
> I'll go ahead and open a JBS ticket to keep the ball rolling on this one,
> and so we have a place to hang some patches and discussions off of. Scream
> if I shouldn't.
>
> -- ramki
>
> On Mon, Aug 12, 2019 at 6:19 PM Ramki Ramakrishna <
> rramakrishna at twitter.com> wrote:
>
>>
>> (Resent... Apologies to anyone who might see duplicates. There was an
>> issue with my membership in the list which, I am guessing, has now been
>> resolved.)
>>
>> ---------- Forwarded message ----------
>> From: Ramki Ramakrishna <rramakrishna at twitter.com>
>> To: hotspot-dev at openjdk.java.net
>> Cc: "Liu, Xin" <xxinliu at amazon.com>, "Mathiske, Bernd" <
>> mathiske at amazon.com>, "Hohensee, Paul" <hohensee at amazon.com>, John
>> Coomes <jcoomes at twitter.com>, Tony Printezis <tprintezis at twitter.com>
>> Bcc:
>> Date: Mon, 12 Aug 2019 15:48:17 -0700
>> Subject: Buffered Logging?
>>
>> In the JDK 7 time-frame, some folks noticed much longer than expected
>> pauses that seemed to coincide with GC logging in the midst of a GC
>> safepoint. In that setup, the GC logs were going to a disk file (these were
>> often useful for post-mortem analyses) rather than to a RAM-based tmpfs
>> which had been the original design center assumption. The vicissitudes of
>> the dirty page flushing policy in Linux when
>> IO load on the machine (not necessarily the JVM process doing the logging)
>> could affect the length and duration of these inline logging stalls.
>>
>> A buffered logging scheme was then implemented by us (and independently by
>> others) which we have used successfully to date to avoid these pauses in
>> high i/o
>> multi-tenant environments.
>>
>> We have recently ported the OpenJDK 8u based scheme past the Unified
>> Logging related changes and have been using it on OpenJDK 11u.
>>
>> In various fora, some of us have heard people express an interest in such
>> an implementation.
>>
>> Would there be appetite for this in openjdk (there are some differences
>> between our scheme in OpenJDK 8u and their subsequent post-Unified-Logging
>> port to OpenJDK 11)?
>>
>> If so, we'd like to open a JBS ticket, attach some patches rebased to
>> current OpenJDK tip, and start preparing a webrev for discussion with a
>> view to possible upstreaming if it converges past review/discussion/debate.
>>
>> PS: In recent discussion at the JVMLS, mention was made of something that
>> might be similar in support of JFR streaming, so our rebase to tip and
>> familiarization with any JFR-associated buffered logging might well make
>> this easier or, possibly, moot.
>>
>> Thoughts, questions, comments, feedback?
>> -- ramki
>>
>> --
>> JVM Team, Platform Engineering, Twitter (San Francisco)
>>
>
>
> --
> JVM Team, Infrastructure Engineering, Twitter (San Francisco)
>


-- 
JVM Team, Infrastructure Engineering, Twitter (San Francisco)