[squeak-dev] Re: How do I debug synchronization problems?

Hi guys,

Managed to narrow this down to a testcase, it seems there is a racecondition at RemoteString>>#Text

http://bugs.squeak.org/view.php?id=7032

Thanks a billion to RandalSchwartz who helped track it down on the squeak IRC channel.

/Johan

On Mon, Apr 28, 2008 at 4:52 PM, Johan Björk jbjoerk@gmail.com wrote:

Hi everyone,

First: sorry for the long email, I have no clue what is going on.

Some background information: I'm running one client to a KomServices TcpService server in squeak 3.9 (MacOSX). I've been doing stresstesting on my server for a while, but previously I never tried to use Squeak at the same time. Today I started using the Process browser to debug another problem, (thanks gokr!) , and noticed that if I opened the Process browser when running a stresstest, I got the most obscure problems.

Now to the problems: First off, I really have NO IDEA what is going on, nor how to debug this. so I'll just plainly state what I see happening, and then someone better then me might be able to explain this, and tell me what more information you guys need:

Starting the process browser, MOST cases, instead of receiving a process browser window, I get a "random" error.

"Random" a bit more specified: Mostly I get Syntax error errors, such as:

---

grimReaperProcess "This is a process which waits for the death of a child OSProcess, and informs any dependents of the change. Use SIGCHLD events if possible, otherwise a Delay to poll for exiting child processes."

    | event processSynchronizationDelay |
    ^ self canAccessSystem
            ifTrue:
                    [event := (self canAccessSystem and: [self canForwardExternalSignals])
                            ifTrue: [self sigChldSemaphore]
                            ifFalse: [Delay forMilliseconds: 200].
                    processSynchronizationDelay := Delay forMilliseconds: 20.
                    grimReaper ifNil:
                            [grimReaper Period or right bracket expected ->

---

parse: sourceStream class: class noPattern: noPattern context: ctxt notifying: req ifFail: aBlock Unmatched comment quote ->"Answer a MethodNode for the argument, sourceStream, that is the root of a parse tree. Parsing is done with respect to the argument, class, to find instance, class, and pool variables; and with respect to the argument, ctxt, to find temporary variables. Errors in parsing are r

---

I also sometimes receive messageNotUnderstood errors, (but I don't have any stacktrace for that, it seems the current image didn't have the HTML exporter installed, and I got other exceptions afterwards) for example: Parser>>parseError

I guess I'm accessing some operation which I'm not allowed to concurrently. Since I don't know where I'm to look, I'll state some things I do and hopefully someone can point me in the right direction: Everything in my application is "singlethreaded" ie, it's only one concurrent connection. I'm NOT using Morphic I'm accessing the #Smalltalk to convert Symbols to classes. I'm using perform: on my own object I'm using instVarNames and classVarNames on about every object in the system I request sub and superclasses for about every object in the system I request sourcecode for both class and instance methods for about every object in the system (sourceCodeAt: #method) I'm never writing or changing anything, all my operations are "read only".

Thanks in advance /Johan

Hi guys,

I've managed to nail it down a bit more.