[Glass] problem update: Zinc server with Seaside (3.1)

Thu Dec 19 16:51:38 PST 2013

Johan,

I've narrowed it down to a problem in SocketStream>>atEnd. Basically SocketStream>>atEnd 
returns <true> if the socket isConnected (whether or not data has been received) which them causes
SocketStream>>next to think that there is data available after the SocketStream>>receiveData call, so
lastRead is incremented and we are off to the races. 

There is a bit more gorey detail here[1].

At a higher level (see logging in [1]) two socket connections are accepted when only one should be (haven't characterized that yet) and the second socket connection has no data and is left open which leads to the 
SocketStream>>atEnd problem...

If you don't see this kind of behavior in Pharo, then perhaps there are differences in how SocketStream>>receiveData ... if SocketStream>>receiveData blocks in Pharo then that would explain why this doesn't happen in Pharo ... 

I may or may not get farther along this evening, but I think we're getting closer ...

Dale

[1] https://github.com/dalehenrich/todeHome/blob/master/home/seaside3.1.0/thoughts

----- Original Message -----
| From: "Johan Brichau" <johan at yesplan.be>
| To: "Dale K. Henrichs" <dale.henrichs at gemtalksystems.com>
| Cc: glass at lists.gemtalksystems.com
| Sent: Thursday, December 19, 2013 7:46:37 AM
| Subject: Re: [Glass] problem update: Zinc server with Seaside (3.1)
| 
| Hi Dale,
| 
| Thanks for these pointers.
| I will look into it asap.
| 
| One thing I noticed is that after I merged the latest changes into
| Seaside3.1 [1], a lot less processes were spawning and it took more
| time before the system ran out of memory.
| But it might just have been a coincidence...
| 
| Johan
| 
| [1] https://github.com/glassdb/Seaside31/pull/5
| 
| On 19 Dec 2013, at 06:38, Dale K. Henrichs
| <dale.henrichs at gemtalksystems.com> wrote:
| 
| > Just a touch more info:
| > 
| > ZnMultiThreadedServer>>listenLoop sents #repeat to a block ...
| > 
| > if `serverSocket isValid` returns false, the loop is exited but it
| > launches another
| > #listenLoop ... if we get consistent invalid serverSockets, this
| > guy will spin out of control..
| > 
| > Inside the block, ZnMultiThreadedServer>>serveConnectionsOn: is
| > called (right before the repeat).
| > 
| > In ZnMultiThreadedServer>>serveConnectionsOn: if #waitForAcceptFor:
| > returns a non-nil response, we are off to the races with a forked
| > process and a return to ZnMultiThreadedServer>>listenLoop which
| > itself spins up a new call to
| > ZnMultiThreadedServer>>serveConnectionsOn: ....
| > 
| > Soooo, it looks like SocketStreamSocket>>waitForAcceptFor: had
| > better function correctly .... and serverSocket had better not go
| > into terminal invalidity...
| > 
| > Some halts or breakpoints in and around these particular methods
| > should yield some good information ... or point us in a more
| > productive direction.
| > 
| > Dale
| > 
| > From: "Dale K. Henrichs" <dale.henrichs at gemtalksystems.com>
| > To: "Johan Brichau" <johan at yesplan.be>
| > Cc: glass at lists.gemtalksystems.com
| > Sent: Wednesday, December 18, 2013 8:59:47 PM
| > Subject: Re: [Glass] problem update: Zinc server with Seaside (3.1)
| > 
| > Johan,
| > 
| > I've collected more info on two processes[1] ... first the one that
| > gets an "index out of range error" and the other process that was
| > sitting in the process list waiting for more input from the
| > socket, but the socket was closed (at leasted #isConnected is
| > false).
| > 
| > I hit the out of memory earlier but didn't collect any meaningful
| > info ... I'm assuming that the multi-threaded boy is hitting an
| > error somewhere and spinning away like crazy ...
| > 
| > Need to catch the error in progress and perhaps find out from Sven
| > if there is supposed to be a "deadman switch" on this guy to avoid
| > infinite errors ..
| > 
| > Dale
| > 
| > [1]
| > https://github.com/dalehenrich/todeHome/blob/master/home/seaside3.1.0/stacks
| > 
| > From: "Dale K. Henrichs" <dale.henrichs at gemtalksystems.com>
| > To: "Johan Brichau" <johan at yesplan.be>
| > Cc: glass at lists.gemtalksystems.com
| > Sent: Wednesday, December 18, 2013 6:39:13 PM
| > Subject: Re: [Glass] problem update: Zinc server with Seaside (3.1)
| > 
| > Here's the stack:
| > 
| > 1. OffsetError(AbstractException)>>_signalWith: @5 line 25
| > 2. OffsetError(AbstractException)>>signal @2 line 47
| > 3. ByteArray(Object)>>_error:args: @15 line 11
| > 4. ByteArray(Object)>>_errorIndexOutOfRange: @2 line 6
| > 5. ByteArray>>at: @4 line 13
| > 6. SocketStream>>next @13 line 10
| > 7. ZnLineReader>>processNext @5 line 4
| > 8. ZnLineReader>>nextLine @3 line 3
| > 9. ZnRequestLine>>readFrom: @3 line 3
| > 10. ZnRequestLine class>>readFrom: @3 line 3
| > 11. ZnRequest>>readHeaderFrom: @2 line 2
| > 12. ZnRequest(ZnMessage)>>readBinaryFrom: @2 line 3
| > 13. ZnRequest class(ZnMessage class)>>readBinaryFrom: @3 line 3
| > 14. [] in
| > ExecBlock1(ZnZincServerAdaptor)>>configureServerForBinaryReading
| > @2 line 4
| > 15. [] in
| > ZnManagingMultiThreadedServer(ZnSingleThreadedServer)>>readRequest:
| > @3 line 6
| > 16. [] in
| > ExecBlock0(ZnSingleThreadedServer)>>withMaximumEntitySizeDo: @2
| > line 6
| > 17. [] in ZnMaximumEntitySize class(DynamicVariable
| > class)>>value:during: @3 line 9
| > 18. ZnMaximumEntitySize class(ExecBlock)>>ensure: @2 line 12
| > 19. ZnMaximumEntitySize class(DynamicVariable class)>>value:during:
| > @6 line 10
| > 20.
| > ZnManagingMultiThreadedServer(ZnSingleThreadedServer)>>withMaximumEntitySizeDo:
| > @5 line 5
| > 21.
| > ZnManagingMultiThreadedServer(ZnSingleThreadedServer)>>readRequest:
| > @2 line 6
| > 22. [] in
| > ZnManagingMultiThreadedServer(ZnMultiThreadedServer)>>readRequestSafely:
| > @2 line 4
| > 23. ZnManagingMultiThreadedServer(ExecBlock)>>on:do: @3 line 42
| > 24.
| > ZnManagingMultiThreadedServer(ZnMultiThreadedServer)>>readRequestSafely:
| > @3 line 5
| > 25.
| > ZnManagingMultiThreadedServer(ZnMultiThreadedServer)>>executeOneRequestResponseOn:
| > @2 line 7
| > 26. [] in
| > ZnManagingMultiThreadedServer(ZnMultiThreadedServer)>>executeRequestResponseLoopOn:
| > @2 line 10
| > 27. [] in ZnCurrentServer class(DynamicVariable
| > class)>>value:during: @3 line 9
| > 28. ZnCurrentServer class(ExecBlock)>>ensure: @2 line 12
| > 29. ZnCurrentServer class(DynamicVariable class)>>value:during: @6
| > line 10
| > 30.
| > ZnManagingMultiThreadedServer(ZnMultiThreadedServer)>>executeRequestResponseLoopOn:
| > @4 line 8
| > 31. [] in
| > ZnManagingMultiThreadedServer(ZnMultiThreadedServer)>>serveConnectionsOn:
| > @2 line 9
| > 32. ZnManagingMultiThreadedServer(ExecBlock)>>ensure: @2 line 12
| > 33. [] in
| > ZnManagingMultiThreadedServer(ZnMultiThreadedServer)>>serveConnectionsOn:
| > @2 line 10
| > 34. [] in ExecBlock0(ExecBlock)>>ifCurtailed: @2 line 6
| > 35. ExecBlock0(ExecBlock)>>ensure: @2 line 12
| > 36. ZnManagingMultiThreadedServer(ExecBlock)>>ifCurtailed: @3 line
| > 8
| > 37. [] in
| > ZnManagingMultiThreadedServer(ZnMultiThreadedServer)>>serveConnectionsOn:
| > @2 line 11
| > 38. GsProcess>>_start @7 line 16
| > 39. UndefinedObject(GsNMethod class)>>_gsReturnToC @1 line 1
| > 
| > 
| > From: "Dale K. Henrichs" <dale.henrichs at gemtalksystems.com>
| > To: "Johan Brichau" <johan at yesplan.be>
| > Cc: glass at lists.gemtalksystems.com
| > Sent: Wednesday, December 18, 2013 6:26:01 PM
| > Subject: Re: [Glass] problem update: Zinc server with Seaside (3.1)
| > 
| > Johan,
| > 
| > I've finally started monkeying with this and the first thing I ran
| > into (running this under tODE and trying to duplicate the GemTools
| > error condition) was an error involving SocketStream and an
| > apparent buffer overflow ... it looks to me that
| > SocketStream>>next has no logic to refill the buffer once it is
| > full ... at least I got a stack in which the ByteArray buffer was
| > accessed at slot 4097 (1 larger than the buffer):
| > 
| > There are three other processes floating around as well ... I'll
| > keep digging ...
| > 
| > Dale
| > 
| > 
| > From: "Johan Brichau" <johan at yesplan.be>
| > To: glass at lists.gemtalksystems.com
| > Sent: Sunday, December 15, 2013 1:20:20 PM
| > Subject: [Glass] problem update: Zinc server with Seaside (3.1)
| > 
| > Hi all,
| > 
| > I’m working on the Zinc server adaptor for Seaside 3.1 but I got
| > stuck.
| > 
| > Launching the following from Gemtools brings up the server and
| > makes it respond to requests nicely. Trying to do the same from a
| > topaz session though, immediately throws an out-of-mem exception.
| > 
| > WAGsZincAdaptor startOn: 8383
| > 
| > If you break the blocking call in Gemtools and run the line above
| > again, you also run out-of-mem after a couple of times (but only
| > after _also_ connecting to the server from your web browser).
| > First question about this is why that does not happen in gem tools?
| > I tried turning the auto commit off but that did not change
| > anything.
| > 
| > Following advice in [1], I started investigating from gemtools and
| > got this for the byte sizes in temp obj memory on 75% full:
| > 
| > #'ByteArray'->22153440, #'GsMethodDictionary'->3073088,
| > #'GsMethodLookupCache'->2224064, #'GsProcess'->562224,
| > #'String'->415504, #'Array'->340168, #'SocketStream'->322680,
| > #'ExecBlock'->201664, #'VariableContext'->175552,
| > #'SocketStreamSocket'->150696,  …0
| > 
| > The process browser shows over 100 threads displayed as follows:
| > 
| > (priority=25) ready [oop= …. ]
| > 
| > I guess this is where Dale started having nightmares. The stack
| > traces show the out-of-mem always happens in the
| > ZnNetworkingUtils>>setSocketStreamParameters: method.
| > 
| > All of this is using the current Zinc version on github for
| > gemstone 3.1 [2]  and my version of the Seaside 3.1 port [3]
| > To try, load Seaside from my repo, load the ‘Zinc-Seaside’ group
| > from the baseline and hit the above.
| > 
| > Any ideas are welcome
| > 
| > Johan
| > 
| > [1]
| > http://gemstonesoup.wordpress.com/2008/11/19/gemstone-101-managing-out-of-memory-situations/
| > [2] https://github.com/glassdb/zinc/tree/gemstone3.1
| > [3] https://github.com/jbrichau/Seaside31
| > 
| > _______________________________________________
| > Glass mailing list
| > Glass at lists.gemtalksystems.com
| > http://lists.gemtalksystems.com/mailman/listinfo/glass
| 
| 