RFR: 8077846: improve locking strategy for readConfiguration(), reset(), and initializeGlobalHandlers() (original) (raw)

Daniel Fuchs daniel.fuchs at oracle.com
Mon May 4 18:52:48 UTC 2015

On 04/05/15 16:46, Peter Levart wrote:

Hi Daniel,

Here it is: http://cr.openjdk.java.net/~plevart/misc/LogManager.synchronization/webrev.04/

Looks good for me Peter :-) Hopefully Mandy will like it too!

All java/util/logging tests pass for me except java/util/logging/TestLoggerWeakRefLeak

#section:build ----------messages:(2/93)---------- command: build jdk.testlibrary.* reason: User specified action: run build jdk.testlibrary.* result: Not run. Test running...

test result: Error. Can't find source file: jdk/testlibrary/*.java in directory-list: /home/peter/work/hg/jdk9-dev/jdk/test/java/util/logging /home/peter/work/hg/jdk9-dev/jdk/test/lib/testlibrary

I assume you may have a somewhat older version of jtreg that doesn't support the .* pattern in @library / @build

I have imported your patch and tested locally - on my machine all the logging tests have passed. I have also run a test campaign against it and things looked good there as well.

best regards,

-- daniel

Regards, Peter On 05/04/2015 04:09 PM, Peter Levart wrote:

On 05/04/2015 03:46 PM, Daniel Fuchs wrote: On 04/05/15 15:26, Peter Levart wrote: Hi Daniel, Mandy,

What about the following: http://cr.openjdk.java.net/~plevart/misc/LogManager.synchronization/webrev.03/

You see, no boolean flags needed. The globalHandlersState is always changed atomically within a locked region, so a graph of transitions can be drawn: http://cr.openjdk.java.net/~plevart/misc/LogManager.synchronization/LogManager.globalHandlersState.png STATEINITIALIZING and STATEREADINGCONFIG are intra-locked-region states used to prevent infinite recursion in initializeGlobalHandlers() and communicating state from within locked-region of readConfiguration() to nested reset(), respectively, but never from one locked region to another. That looks better. I would consider removing these lines: 1333 if (globalHandlersState == STATESHUTDOWN) { 1334 // already in terminal state 1335 return; 1336 } in favor of: 1354 } else if (globalHandlersState != STATESHUTDOWN) { 1355 // ...user calling reset()... and let the reset reset twice if it's called from different contexts. There may be permissions that could prevent a user-called reset() to close all handlers, and we don't want that to prevent the Cleaner-called reset to come afterwards and perform its job. Then we don't need STATESHUTTINGDOWN. Cleaner.run() can change directly to STATESHUTDOWN and reset() would just leave it there, but perform the reset anyway. Will create another variant including your test too. Regards, Peter BTW - in the end - one of us will need to push this together with the new test :-) cheers, -- daniel

Regards, Peter On 05/01/2015 02:03 AM, Peter Levart wrote:

On 04/30/2015 04:42 PM, Daniel Fuchs wrote: On 28/04/15 17:46, Peter Levart wrote:

On 04/28/2015 04:57 PM, Daniel Fuchs wrote: Here's my attempt at simplifying this: http://cr.openjdk.java.net/~plevart/misc/LogManager.synchronization/webrev.01/

LogManager can be subclassed, and subclasses may override reset() for different purposes. So I'm afraid the Cleaner thread still needs to call te public reset() method. The same unfortunately applies to readConfiguration(). best regards, -- daniel Um, yes of course. This can be fixed: http://cr.openjdk.java.net/~plevart/misc/LogManager.synchronization/webrev.02/ Hi Peter, Sorry for the late reply. My gut feeling is that I dislike multi-state ints. But I guess that's a matter of taste - so I could probably overcome it ;-) Isn't that a simplification (of reasoning)? In particular if individual boolean flags are read and/or written without holding any lock. What makes me less happy is that I had managed to remove the explicit synchronized() { } block in the Cleaner thread - and I now see it's back. Could we maybe keep the imminentDeath boolean and remove the explicit locking in the Cleaner thread? I mean... imminentDeath should be checked from within the lock - before doing anything. But it does not need to be set from within a locked section. best regards, -- daniel Hi Daniel, Mandy, Explicit locking in Cleaner is something that is performed in reset() anyway, so getting rid of it is not actually getting rid of it, as Cleaner is calling reset() anyway. The lock is reentrant. But If you want get rid of it so that reset() is not called under lock held because reset() might be overridden, then imminentDeath must return. @Mandy: In webrev.01 we had a private reset(int newState), called from reset(), Cleaner and readConfiguration(), but Daniel then spotted that reset() is an overridable method, so it has to be called from Cleaner and readConfiguration() too, unfortunately. The STATEXXX names are best depicted if looking at code in initializeGlobalHandlers() method. Let me prepare a changed webrew... Regards, Peter

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