Comment #25 on issue 4768 by
[hidden email]: Code loading/compilation
followed by starting a TCP server results in a hang
http://code.google.com/p/pharo/issues/detail?id=4768Hi
I saw the change and although it seems to work it masks somewhat what the
real issue was. i.e. The fix is to do what the Processor>>yield primitive
does manually.
It looks like the issue is to do the priority of the processes. The Delay
timer event loop is set to TimingPriority := 80.
Delay class>startTimerEventLoop
...
TimerEventLoop priority: Processor timingPriority.
...
In BlockClosure>>valueUnpreemptively the code 'Processor highestPriority.'
answers 80 too. We only call Processor yield after changing the current
process back to it's original priority, but surely this could cause an
issue for any code that was at the highest priority?
So I'd recommend to change the code to be as below
BlockClosure>>valueUnpreemptively
"Evaluate the receiver (block), without the possibility of preemption by
higher priority processes. Use this facility VERY sparingly!"
"Think about using Block>>valueUninterruptably first, and think about
using Semaphore>>critical: before that, and think about redesigning your
application even before that!
After you've done all that thinking, go right ahead and use it..."
| activeProcess oldPriority result semaphore |
activeProcess := Processor activeProcess.
oldPriority := activeProcess priority.
activeProcess priority: Processor highestPriority.
result := self ensure: [ Processor yield. activeProcess priority:
oldPriority.].
"Yield after restoring priority to give the preempted processes a chance
to run"
^result
i.e. the change is to this line: result := self ensure: [ Processor yield.
activeProcess priority: oldPriority.].
Rather yield the current highest priority before reverting the priorities.
It seems to work but not sure if we should yield again after reverting the
priorities as well?
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