[Vm-dev] Minheadless trial

Wed Aug 8 13:39:13 UTC 2018

On 7 August 2018 at 19:47, Ben Coman <btc at openinworld.com> wrote:
>
>  it gets stuck the following loop...  https://github.com/bencoman/
opensmalltalk-vm/blob/8231b96f9b/platforms/win32/vm/
sqWin32SpurAlloc.c#L139-L183

whoops, that was meant to be the minheadless file....
https://github.com/bencoman/opensmalltalk-vm/blob/8231b96f9b/platforms/minheadless/windows/sqWin32SpurAlloc.c#L140-L184

In the meantime, I'll forge ahead to play with  osvm_run();
>

I've hardly used Visual Studio before, and never combined with CMake,
so I'll record a few things I discover in case others might find it
interesting or advise a better way.

To try with the Stack Interpreter first, in CMakeLists.txt changed...
    option(COG_JIT "Cog JIT" ON)
to...
    option(COG_JIT "Cog JIT" OFF)
then cleared the cache... Right-clicked on "CMakeLists.txt >
Cache(x64-Debug only) > Delete cache folder..."
otherwise it didn't seem to pick up that change.

To give the VM an image to run and something to do...
Right-clicked on "CMakeLists.txt > Debug and Launch Settings > pharo.exe"
then edited the presented "launch.vs.json" as follows...
{
  "version": "0.2.1",
  "defaults": {},
  "configurations": [
    {
      "type": "default",
      "project": "CMakeLists.txt",
      "projectTarget": "pharo.exe (dist\\pharo.exe)",
      "name": "pharo.exe minImage+eval (dist\\pharo.exe)",
      "args": [
        "C:\\#Dev\\latest-minimal-64\\Pharo7.0-metacello-64bit-65cff7b.image
eval 19 + 23",
      ]
    },
  ]
}

Then... "CMake > Build All"
followed by starting... "x64-Debug" with "pharo.exe minImage+eval"
which opened a console window that doesn't do much besides output like
this...
GIV(remapBufferCount) == 0 47923

Now I notice the file "dist\stderr" says...
    "Your VM is too old for this image. Please download the latest VM."
so probably I need to run "scripts\updateSCCSVersions"
but thats a shell script.  How to run it under Windows?

Luckily my installed Git Windows has Git Bash which opens a cygwin
environment.
where I do...
   cd /c/#Repos/OpenSmalltalk/opensmalltalk-vm/
   ./scripts/ updateSCCSVersions

Now to give a bit more visibility to program execution,
in "spurstack64src/interp.c" I inserted the following into main interpreter
loop...

"+" unsigned long long debugCountBytecode = 0;
while (1) {
"+" debugCountBytecode += 1;
"+" if ((debugCountBytecode % 100000 == 0))
"+" {
"+" printf("%llu\n", debugCountBytecode);
"+" }

Then... "CMake > Build All"
followed by starting... "x64-Debug" with "pharo.exe minImage+eval"
which opened a console window with the following output...
GIV(remapBufferCount) == 0 47923
GIV(remapBufferCount) == 0 42469
100000
200000
300000
400000
500000
600000
700000
800000
900000
1000000
1100000
1200000
1300000
1400000
1500000

and updated contents of these files... yay!
    dist\stderr ==> #'EvaluateCommandLineHandler successfully finished'
    dist\stdout ==> 42

However the VM/Image keeps running.   Adding "--quit" to the command line
didn't help.
I'm not really familiar with the command line handlers.
Doing... "Debug > Break All"
bring me up some warnings like...
  "winmm.pdb not loaded"
  "winmm.pdb contains the debug information required to find the source for
the module winmm.dll"

Never heard of a PDB, but loaded them by following these instructions...
   "Specify Symbol (.pdb) and Source Files in the Visual Studio Debugger"
   https://msdn.microsoft.com/en-us/library/ms241613.aspx
and learnt a lot more about them...
  "PDB Files: What Every Developer Must Know"
  https://www.wintellect.com/pdb-files-what-every-developer-must-know/
Now the next few times I started...  "x64-Debug" with "pharo.exe
minImage+eval"
it got hung up downloading the symbols.  I had to terminate & restart
debugging it a few times
as it progressed a bit each time.

When finally got running again and after 1500000 printed I did...  "Debug >
Break All"
and... "Debug > Windows > Threads" and now it shows the proper names rather
than just addresses...

A little surprised by the number of threads.
No clue what ntdll.dll!NtWaitForWorkViaWorkerFactory
or winmm.dll!timeThread are, but leave that for later.

Now with all thread stopped, trying... "Debug > Windows > Parallel
Stacks"...

shows the two application threads are "in external code"
invoked from  ioRelinquishProcessorForMicroseconds()  and
beatThreadStateMachine().
Clicking on each of those displays their source code indicating the
"external code"
for each is  MsgWaitForMultipleObjects()  and  WaitForSingleObject()
respectively  .

Its very easy to flip back and forth between the two application threads,
stepping-out of the "external code" with Shift-F11, to observe a tiny
window of VM operation.

Well thats enough for one post!
Success running a MSVC compiled Spur Stack "minheadless" VM.

Next I'll try...    option(COG_JIT "Cog JIT" ON)

cheers -ben

P.S.  Definitions for the curious...

sqInt
ioRelinquishProcessorForMicroseconds(sqInt microSeconds)
{
    /* wake us up if something happens */
    ResetEvent(vmWakeUpEvent);
    MsgWaitForMultipleObjects(1, &vmWakeUpEvent, FALSE, microSeconds /
1000, QS_ALLINPUT);
    ioProcessEvents(); /* keep up with mouse moves etc. */
    return microSeconds;
}

static DWORD WINAPI
beatThreadStateMachine(void *careLess)
{
beatThreadState = active;
while (beatThreadState != condemned) {
DWORD res = WaitForSingleObject(beatSemaphore, beatThreadState == active ?
beatMilliseconds : INFINITE);
if (res == WAIT_TIMEOUT)
heartbeat();
else if (res == WAIT_FAILED)
abortMessage(TEXT("Fatal: WaitForSingleObject(beatSemaphore) %ld"),
GetLastError());
else
printLastError(TEXT("beatThreadStateMachine WaitForSingleObject"));
}
beatThreadState = dead;
return 0;
}
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