[squeak-dev] [Vm-dev] Difficult to debug VM crash with full blocks and Sista V1Nicola Mingotti nmingotti at gmail.comSat Sep 14 05:18:05 UTC 2019
I gave a super-fast & superficial read to the answers. The GUI tool should exist, I can google it. The first answer was edited in 2017, the rest, as you say, is very old. E.G. they talk about 'ipfw' which is one of the FreeBSD firewalls and the main entry point to 'dummynet' but, if I 'apropos ipfw' in my macOS I find nothing. If the GUI works well enough, use that. dummynet is powerful but requires several hours of study end experiments. bye n. On 9/13/19 10:02 PM, Phil B wrote: > I'm sure you're right (assuming the GUI tool still exists... the top > answer is quite old.) Mainly I linked to the answer since it seems to > cover a spectrum of approaches which might Eliot might find useful. > > On Sat, Sep 14, 2019 at 12:52 AM Nicola Mingotti <nmingotti at gmail.com > <mailto:nmingotti at gmail.com>> wrote: > > > With high probability that GUI-tool is a wrapper to 'dummynet'. > Anyhow, for sure it will be faster to deploy. > > n. > > > On 9/13/19 9:32 PM, Phil B wrote: >> It sounds like simulating a terrible (dropping packets) or >> painfully slow (kbps speeds) network connection might be a more >> controlled way to reproduce the issue: >> https://apple.stackexchange.com/questions/24066/how-to-simulate-slow-internet-connections-on-the-mac >> >> On Fri, Sep 13, 2019 at 11:16 PM Eliot Miranda >> <eliot.miranda at gmail.com <mailto:eliot.miranda at gmail.com>> 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 >> >> > -------------- next part -------------- An HTML attachment was scrubbed... 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