Re: Freeing a list bound to a hash will cause a crash

On Mar 7, 2004, at 6:37 PM, Eric DeWitt wrote:

> Code that causes the crash is listed below.  All crashed threads are 
> at (repeats every time) is 'stEvalFree'.

Yep -- and I was just looking at the code you sent last week, and that 
also turned out to be the same issue.  If there is any non-object 
element in a list, "free" will trigger a crash.

This will be fixed for the next release, but in the meantime, simply 
don't free lists unless they contain only objects :).

Lists are garbage collected automatically, so you should never have to 
manually "free the list".  Calling free with a list is simply a 
shortcut for calling free with each element of the list.

- jon klein

> Controller myController.
>
> Control: myController {
>     + variables:
>       testHash (hash).
>       myList (list).
>
>     + to init:
>         myList = {{"foo", 0}, "bar"}.
>         testHash{"foo"} = myList.
>         print testHash{"foo"}.
>
>     + to iterate:
>
>         free myList.
>         if (testHash{"foo"}): print testHash{"foo"}.
>
>         super iterate.
> }
>
>
> Date/Time:  2004-03-07 18:30:54 -0500
> OS Version: 10.2.8 (Build 6R73)
> Host:       sibeling.local.
>
> Command:    breve
> PID:        16892
>
> Exception:  EXC_BAD_ACCESS (0x0001)
> Codes:      KERN_PROTECTION_FAILURE (0x0002) at 0x00000002
>
> Thread 0:
>  #0   0x9003e9a8 in semaphore_wait_signal_trap
>  #1   0x9003e7c4 in _pthread_cond_wait
>  #2   0x97df1868 in -[NSRecursiveLock lock]
>  #3   0x000115c8 in -[slBreve updateLog:] (crt.c:300)
>  #4   0x97df4dc0 in __NSFireTimer
>  #5   0x90163230 in __CFRunLoopDoTimer
>  #6   0x90148d28 in __CFRunLoopRun
>  #7   0x90180f58 in CFRunLoopRunSpecific
>  #8   0x969a3b70 in RunCurrentEventLoopInMode
>  #9   0x969b3a78 in ReceiveNextEventCommon
>  #10  0x969dabbc in BlockUntilNextEventMatchingListInMode
>  #11  0x9308dedc in _DPSNextEvent
>  #12  0x930a0158 in -[NSApplication 
> nextEventMatchingMask:untilDate:inMode:dequeue:]
>  #13  0x930b1d88 in -[NSApplication run]
>  #14  0x9315fc58 in NSApplicationMain
>  #15  0x00009f44 in _start (crt.c:267)
>  #16  0x00009db8 in start
>
> Thread 1:
>  #0   0x90073ba8 in mach_msg_trap
>  #1   0x90005ed0 in mach_msg
>  #2   0xc0009190 in __ape_internal
>  #3   0xc0000efc in __ape_agent
>  #4   0x90020c28 in _pthread_body
>
> Thread 2:
>  #0   0x9003e9a8 in semaphore_wait_signal_trap
>  #1   0x9003e7c4 in _pthread_cond_wait
>  #2   0x97e34088 in -[NSConditionLock lockWhenCondition:]
>  #3   0x930819a0 in -[NSUIHeartBeat _heartBeatThread:]
>  #4   0x97e2cc38 in forkThreadForFunction
>  #5   0x90020c28 in _pthread_body
>
> Thread 3:
>  #0   0x90073ba8 in mach_msg_trap
>  #1   0x90005ed0 in mach_msg
>  #2   0x901489f0 in __CFRunLoopRun
>  #3   0x90180f58 in CFRunLoopRunSpecific
>  #4   0x94652f80 in _ZN10HALRunLoop9OwnThreadEPv
>  #5   0x946591e0 in _ZN9CAPThread5EntryEPS_
>  #6   0x90020c28 in _pthread_body
>
> Thread 4 Crashed:
>  #0   0x0001a6f8 in stEvalFree (crt.c:300)
>  #1   0x0001fee0 in stEvalExp (crt.c:300)
>  #2   0x0001a814 in stEvalArray (crt.c:300)
>  #3   0x0001e320 in stCallMethod (crt.c:300)
>  #4   0x00023f44 in brEngineIterate (crt.c:300)
>  #5   0x00013804 in -[slBreveEngine runWorld:] (crt.c:300)
>  #6   0x97e2cc38 in forkThreadForFunction
>  #7   0x90020c28 in _pthread_body
>
> PPC Thread State:
>   srr0: 0x0001a6f8 srr1: 0x0000f030                vrsave: 0x00000000
>    xer: 0x00000000   lr: 0x0001a608  ctr: 0x0001a050   mq: 0x00000000
>     r0: 0x00000009   r1: 0xf01e2900   r2: 0x0001a608   r3: 0x00000000
>     r4: 0x00000002   r5: 0x02dc0780   r6: 0x00000000   r7: 0x0001f008
>     r8: 0x00019ff4   r9: 0x02dc0760  r10: 0x00019fb8  r11: 0x00000000
>    r12: 0x00000000  r13: 0x00133724  r14: 0x00133724  r15: 0x0013ab18
>    r16: 0x00000000  r17: 0x02dc2990  r18: 0x00115ae0  r19: 0x0013ac20
>    r20: 0x00000000  r21: 0x00000000  r22: 0x02dbc5e0  r23: 0x00000000
>    r24: 0xf01e2d40  r25: 0x0001ee6c  r26: 0x0001edb0  r27: 0x00000000
>    r28: 0x02dbc5e0  r29: 0x000fa5ec  r30: 0x02dc08a0  r31: 0x0001a5ec
>
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