> On 14.09.2019, at 06:03, Nicola Mingotti <nmingotti at gmail.com> wrote:
> 
> 
> I can help you a bit only on this point:
> "- is there a way of introducing network delays in Mac OS that might help me induce the bug?"

Yea it is called "network link conditioner.prefpane" :D


> 
> Yes, in theory it is possible. Some time ago I red the documentation of 'dummynet' in FreeBSD for the firewall 'ipfw', it seemed to be very interesting but I never had occasion to use it.
> 
> Now, Apple Unix is in large part taken from FreeBSD => I check if they took also dummynet:
> macOS> apropos dummynet
> dummynet(4) .... 
> 
> So, yes, it is there.
> 
> HTH
> 
> bye
> Nicola
> 
> 
> 
> 
>  
> 
> 
> 
> 
> On 9/13/19 8:15 PM, Eliot Miranda wrote:
>> Hi All,
>> 
>>     there is a VM bug in 64-bit Spur with the Sista V1 bytecode set and full blocks.  The symptom is that when waiting for a remote Monticello repository to update and/or deliver a package version the system crashes in JITTED code after what appears to be some kind of wait.
>> 
>> This is a reliably occurring bug b ut maddeningly difficult to reproduce.  The bug reliably occurs when interacting with a remote rep[ository (e.g. http://source.squeak.org/VMMaker) when the server is "cold", and hence makes the image wait.  Every time I have tried to repeat the failing sequence the crash has not occurre3d, I think because the server is now "hot" and serves up the version quickly.  Today I even tried shutting down my machine for over an hour and rebooting.  But I could not get the crash to occur even though it seems to me that every time I try it the first time in the4 day it does crash.
>> 
>> This is an important bug to fix.  If it cannot be fixed then full blocks and Sista V1 are not ready for use in the upcoming Squeak release.  I am looking for help in debugging this.
>> 
>> - is anyone else uising the 64-bit VM with full blocks and Sista V1 who sees hard VM crashes?  If so, under what circumstances?
>> 
>> - is it possible to flush caches in the http://source.squeak.org/VMMaker server, or could people tolerate me rebooting the server?
>> 
>> - is there a way of introducing network delays in Mac OS that might help me induce the bug?
>> 
>> - can anyone think of any other strategies I might take to try and reproduce this?
>> 
>> I may have to try and reproduce e the bug in the simulator to have a chance of identifying the bug.  Does anyone have a good enough mental model of the Monticello server interaction and have energy to help me figure this one out?
>> 
>> Here is some information from the last crash I did see in the debugger (alas it is incomplete; there are a number of additional pieces of info I could have collected).
>> 
>> (lldb) thr b
>> * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)
>>   * frame #0: 0x000000010de5700a
>>     frame #1: 0x000000010dd7b174
>>     frame #2: 0x000000010dd45f1c
>>     frame #3: 0x000000010dd44534
>>     frame #4: 0x000000010dd44c60
>> (lldb) x/10i 0x000000010de5700a
>> 
>> (lldb) call printStackCallStackOf($rbp)
>>     0x7ffeefbdfc30 M Heap>upHeap: 0x11273ca90: a(n) Heap
>>     0x7ffeefbdfc68 M Heap>add: 0x11273ca90: a(n) Heap
>>     0x7ffeefbdfca0 M Delay class>scheduleDelay:from: 0x1123ebfb8: a(n) Delay class
>>     0x7ffeefbdfcf0 M Delay class>handleTimerEvent 0x1123ebfb8: a(n) Delay class
>>     0x7ffeefbdfd20 M Delay class>runTimerEventLoop 0x1123ebfb8: a(n) Delay class
>> 
>> (lldb) x/10i 0x000000010dd7b174
>>     0x10dd7b174: 48 8b 55 10  movq   0x10(%rbp), %rdx
>>     0x10dd7b178: 48 89 ec     movq   %rbp, %rsp
>>     0x10dd7b17b: 5d           popq   %rbp
>>     0x10dd7b17c: c2 10 00     retq   $0x10
>>     0x10dd7b17f: cc           int3
>>     0x10dd7b180: cc           int3
>>     0x10dd7b181: cc           int3
>>     0x10dd7b182: cc           int3
>>     0x10dd7b183: cc           int3
>>     0x10dd7b184: cc           int3
>> (lldb) print whereIs(0x000000010dd7b174)
>> (char *) $0 = 0x00000001000f83ff " is in generated methods"
>> (lldb) call printCogMethodFor((void *)0x000000010dd7b174)
>>        0x10dd7afc0 <->        0x10dd7b198: method:        0x112f23c10 selector:        0x112232c20 add:
>> (lldb) print whereIs(0x000000010de5700a)
>> (char *) $1 = 0x00000001000f83ff " is in generated methods"
>> (lldb) call printCogMethodFor((void *)0x000000010de5700a)
>>        0x10de56ba0 <->        0x10de57078: method:        0x1126ec218 prim 23856 selector:     0x7ffeefbf3d20
>> 
>> this method ends up being the fitted version of Delay class>> startTimerEventLoop
>> _,,,^..^,,,_
>> best, Eliot
>> 
>> 
> 
>