Oh, and there's one related question.
It seems to me particularly weird that if sockets caused by the stale OSCs
exceed the ulimit, the threads which use these sockets hang. Is that the normal
and presumed behaviour? I would expect myself an exception thrown instead, or
something like that. Nevertheless, that's not what happens; those threads are
simply stuck in reading from the database forever, like this (jstack output):
===
Thread t@37443: (state = IN_NATIVE)
- java.net.SocketInputStream.socketRead0(java.io.FileDescriptor, byte[], int,
int, int) @bci=0 (Compiled frame; information may be imprecise)
- java.net.SocketInputStream.read(byte[], int, int) @bci=84, line=129
(Compiled frame)
- java.net.SocketInputStream.read() @bci=23, line=182 (Compiled frame)
- java.io.FilterInputStream.read() @bci=4, line=66 (Compiled frame)
- com.frontbase.jdbc.FBJSocket.readInt() @bci=4 (Compiled frame)
- com.frontbase.jdbc.FBJSocket.checkForSecureCommunication() @bci=1
(Interpreted frame)
- com.frontbase.jdbc.FBJConnection.createConnection() @bci=709 (Interpreted
frame)
- com.frontbase.jdbc.FBJConnection.<init>(com.frontbase.jdbc.FBJURL) @bci=116
(Interpreted frame)
- com.frontbase.jdbc.FBJDriver.connect(java.lang.String, java.util.Properties)
@bci=22 (Interpreted frame)
- java.sql.DriverManager.getConnection(java.lang.String, java.util.Properties,
java.lang.ClassLoader) @bci=210, line=582 (Interpreted frame)
- java.sql.DriverManager.getConnection(java.lang.String, java.util.Properties)
@bci=7, line=154 (Interpreted frame)
- com.webobjects.jdbcadaptor.JDBCContext.connect() @bci=251, line=236
(Interpreted frame)
- er.extensions.jdbc.ERXJDBCAdaptor$Context.connect() @bci=29, line=404
(Interpreted frame)
- com.webobjects.jdbcadaptor.JDBCContext._tryConnect() @bci=55, line=362
(Interpreted frame)
- com.webobjects.jdbcadaptor.JDBCContext._channelWillOpen() @bci=8, line=505
(Interpreted frame)
- com.webobjects.jdbcadaptor.JDBCChannel.openChannel() @bci=17, line=111
(Interpreted frame)
-
com.webobjects.eoaccess.EODatabaseContext._openChannelWithLoginPanel(com.webobjects.eoaccess.EODatabaseChannel)
@bci=19, line=1907 (Compiled frame)
- com.webobjects.eoaccess.EODatabaseContext._obtainOpenChannel() @bci=62,
line=1966 (Compiled frame)
-
com.webobjects.eoaccess.EODatabaseContext._objectsWithFetchSpecificationEditingContext(com.webobjects.eocontrol.EOFetchSpecification,
com.webobjects.eocontrol.EOEditingContext) @bci=209, line=3054 (Compiled frame)
-
com.webobjects.eoaccess.EODatabaseContext.objectsWithFetchSpecification(com.webobjects.eocontrol.EOFetchSpecification,
com.webobjects.eocontrol.EOEditingContext) @bci=34, line=3195 (Compiled frame)
-
com.webobjects.eocontrol.EOObjectStoreCoordinator.objectsWithFetchSpecification(com.webobjects.eocontrol.EOFetchSpecification,
com.webobjects.eocontrol.EOEditingContext) @bci=97, line=488 (Compiled frame)
-
com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(com.webobjects.eocontrol.EOFetchSpecification,
com.webobjects.eocontrol.EOEditingContext) @bci=79, line=4069 (Interpreted
frame)
-
er.extensions.eof.ERXEC.objectsWithFetchSpecification(com.webobjects.eocontrol.EOFetchSpecification,
com.webobjects.eocontrol.EOEditingContext) @bci=10, line=1308 (Interpreted
frame)
-
com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(com.webobjects.eocontrol.EOFetchSpecification)
@bci=3, line=4444 (Interpreted frame)
-
er.extensions.eof.ERXEOGlobalIDUtilities.fetchObjectsWithGlobalIDs(com.webobjects.eocontrol.EOEditingContext,
com.webobjects.foundation.NSArray, boolean) @bci=325, line=290 (Interpreted
frame)
-
er.extensions.eof.ERXEOGlobalIDUtilities.fetchObjectsWithGlobalIDs(com.webobjects.eocontrol.EOEditingContext,
com.webobjects.foundation.NSArray) @bci=3, line=229 (Interpreted frame)
-
er.extensions.eof.ERXEOGlobalIDUtilities.fetchObjectWithGlobalID(com.webobjects.eocontrol.EOEditingContext,
com.webobjects.eocontrol.EOGlobalID) @bci=9, line=209 (Interpreted frame)
-
er.extensions.eof.ERXEOGlobalIDUtilities$fetchObjectWithGlobalID.call(java.lang.Object,
java.lang.Object, java.lang.Object) @bci=18 (Interpreted frame)
- others.ImportCSVTask.performAction() @bci=437, line=229 (Interpreted frame)
- er.extensions.concurrency.ERXLongResponseTask$DefaultImplementation.run()
@bci=25, line=166 (Interpreted frame)
- java.lang.Thread.run() @bci=11, line=695 (Interpreted frame)
- er.extensions.concurrency.ERXLongResponseTask$WorkerThread.run() @bci=1,
line=64 (Interpreted frame)
===
Thanks for any insight,
OC
> On 29. 6. 2020, at 4:12 PM, ocs--- via Webobjects-dev
> <webobjects-dev@lists.apple.com> wrote:
>
> Hi there,
>
> it seems finally I succeeded to find the culprit of the problem described
> below. Far as my testing shows, it seems an ObjectStoreCoordinator is never
> garbage collected (presumed it has been used at least once for a fetch).
> Since the OSC opens a socket to the database, this leads to the problem with
> a number of open sockets for a process. Far as my testing shows, the only way
> to make it to do poof is to call dispose manually, which seems a bit at the
> unexpected side, at least for me.
>
> My current test code looks like this:
>
> ===
> class MainPage extends OCSComponent {
> def test {
> def osc=new OCSOSC(),ec=new OCSEC(osc)
> println "created $osc and $ec"
> def obj=EOUtilities.objectWithPrimaryKeyValue(ec,'DBAuction',1000001)
> //[FETCH]
> println "got obj $obj and dying..."
> ec=nil
> osc.dispose() //[WHATTHE]
> osc=nil
> System.gc()
> nil
> }
> }
> class OCSOSC extends EOObjectStoreCoordinator {
> void finalize() {
> println "### $this about to die"
> }
> }
> @InheritConstructors class OCSEC extends ERXEC {
> void finalize() {
> println "### $this about to die"
> }
> }
> ===
>
> If both the lines marked [FETCH] and [WHATTHE] above are commented out, i.e.,
> if the OSC never fetches, both the osc and ec objects report finalizing
> without a need to dispose.
>
> Nevertheless, once the fetch happens as above, [WHATTHE] must be active too —
> otherwise only ec gets garbage collected; osc never ever does (and
> subsequently also never releases its DB socket).
>
> Well the explicit dispose seems to be the fix for my problem, so far it seems
> to work properly; but since I did not find any mention of calling dispose
> manually nor using a dispose registry in the documentation (otherwise than
> those two registries related to archivation and D2JClient), I wonder whether
> this is the proper approach, or whether I am doing something wrong and sooner
> or later I am in for an ugly surprise? Any insight here?
>
> Thanks a lot,
> OC
>
>> On 21. 5. 2020, at 1:13 PM, OCsite <o...@ocs.cz <mailto:o...@ocs.cz>> wrote:
>>
>> Hi there,
>>
>> bumped lately into another weird problem. We import some data into DB in
>> background tasks. Up to yesterday, it worked normally; today six import
>> tasks were launched, and each of them seemingly hang in its first DB
>> operation. Restart did help; alas, the site admins did not try to ask JVM to
>> detect deadlocks when they restarted the application.
>>
>> The background task looks like this:
>>
>> ===
>> class ImportCSVTask extends ERXLongResponseTask.DefaultImplementation {
>> def performAction {
>> _thread.priority=Thread.MIN_PRIORITY
>> try {
>> try {
>> editingContext=ERXEC.newEditingContext(objectStore=new
>> EOObjectStoreCoordinator())
>> editingContext.lock()
>> lognow 1, "=== preparing CSV import in EC $editingContext
>> ==="
>>
>> formPrototype=ERXEOGlobalIDUtilities.fetchObjectWithGlobalID(editingContext,formPrototypeGID)
>> lognow 1, "=== local prototype $formPrototype ==="
>> ... ...
>> ===
>>
>> Always the “preparing” log was the last thing those threads presented; none
>> of them ever reported “local prototype”. There's no other related log in
>> there.
>>
>> Meantime the application ran normally and the worker tasks communicated with
>> the database all right (with an occasional report that some select took
>> 70-odd ms from ERXAdaptorChannelDelegate, we have the threshold at 50). We
>> run with ERXObjectStoreCoordinatorPool.maxCoordinators=1.
>>
>> Any idea what could have gone wrong and how to find the culprit and prevent
>> the problem in future? I thought a new EC in a new OSC can't be blocked for
>> long, but self-evidently, I was wrong, they seemed to lock indefinitely
>> (application was restarted ten-odd hours after the first import hanged after
>> its “preparing” report, still no “local prototype”).
>>
>> Thanks and all the best,
>> OC
>>
>
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