Hi David,
On Mon, Mar 6, 2017 at 5:50 PM, David T. Lewis lewis@mail.msen.com wrote:
In the VM, the millisecond clock wraps within the 32 bit integer range:
#define MillisecondClockMask 0x1FFFFFFF
In the Cuis image, Delay class>>handleTimerEvent does this:
nextTick := nextTick min: SmallInteger maxVal.
On a 64-bit Spur image, SmallInteger maxVal is 16rFFFFFFFFFFFFFFF, but on a 32-bit image it is 16r3FFFFFFF.
Could that be it?
I don't really know how to test in Squeak. As you say, Squeak is now using the microsecond clock in #handleTimerEvent. I do not see anything in primitiveSignalAtMilliseconds that would behave any differently on a 64 bit versus 32 bit image or VM, but I do not know how to test to be sure.
I bet that the following code from primitiveSignalAtMilliseconds ends up wrapping when given Delay primSignal: s atMilliseconds: Time primMillisecondClock - 10.
deltaMsecs := msecs - (self ioMSecs bitAnd: MillisecondClockMask). deltaMsecs < 0 ifTrue: [deltaMsecs := deltaMsecs + MillisecondClockMask + 1]. nextWakeupUsecs := self ioUTCMicroseconds + (deltaMsecs * 1000).
and I bet you'll find that the VM will wake up in about 6 days and 5 hours ;-)
I suppose we could fix this, but I'm *much* happier to simply not use primitiveSignalAtMilliseconds and stay with the simpler and wrapping-immune primitiveSignalAtUTCMicroseconds
Dave
On Mon, Mar 06, 2017 at 11:06:22AM -0300, Juan Vuletich wrote:
I finally understood what was happening. The problem with is primitive
136:
primSignal: aSemaphore atMilliseconds: aSmallInteger "Signal the semaphore when the millisecond clock reaches the value of the second argument. Fail if the first argument is neither a Semaphore nor nil. Essential. See Object documentation whatIsAPrimitive." <primitive: 136> ^self primitiveFailed
If the requested tick is already in the past, all the VMs except for Spur-64 will signal the semaphore anyway. Spur-64 won't. Taking care of this in the Cuis image was easy enough.
Squeak seems not to be affected because it uses a newer primitive, that takes the large integer microsecond ticker, that might have the older behavior (signaling anyway). I'm not really sure, and maybe someone could check the primitive behavior and the corresponding assumptions in Squeak.
Older Squeak images are not affected, as they are all 32-bit. So maybe there's no action required. In any case, making the behavior consistent across VMs and in both primitives would be nice.
Cheers,
On 3/3/2017 3:55 PM, Juan Vuletich wrote:
Hi Folks,
Today, I was able to get closer to the origin of the problem. The problem is when Morphic tries to do a Delay (inter-cycle-pause) of 1 or two milliseconds. (Usually they are quite larger, and the problem does not appear). With the 64-bit VM, sometimes very short delays hang the complete system. I don't know why, but this:
waitDelay _ Delay forMilliseconds: 50. [ true ] whileTrue: [ 1000 atRandom print. waitDelay setDelay: 1; wait ].
is enough to hang Cuis in a short time. When trying to reproduce the problem in Squeak I had mixed results. It doesn't seem to hang there, but if I let this run for a couple of minutes and then try to halt with alt-. , then the hang occurs, and Squeak becomes irresponsibe. As a workaround, in Cuis in the inter cycle pause, I'm avoiding very short delays.
I'm not sure if the bug is in the VM, in the image, or both, but it is still there, and it also affects Squeak. I haven't tried it, but Pharo might also have the problem (if not, it can show a possible solution).
BTW, Bert, I guess Squeak never does short delays in #interCyclePause:
...
Thanks,
On 2/6/2017 12:28 PM, Bert Freudenberg wrote:
Yes, I tried with Spur64. Have not seen it freeze yet on Mac in Squeak, but we possibly have not replicated the test well enough yet.
It *did* freeze in Cuis Spur64 on Mac too.
- Bert -
On Mon, Feb 6, 2017 at 2:08 PM, Juan Vuletich <juanvuletich@zoho.com mailto:juanvuletich@zoho.com> wrote:
Were you usig Spur64? On Debian it does not freeze with CogV3 or Spur32. Only with Spur64.
Thanks, Juan
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---- On Mon, 06 Feb 2017 09:19:48 -0300 *bert@freudenbergs.de <mailto:bert@freudenbergs.de> * wrote ---- On Mon, Feb 6, 2017 at 3:15 AM, David T. Lewis <lewis@mail.msen.com <mailto:lewis@mail.msen.com>> wrote: It would be interesting to try reproducing this in a Squeak image, but I have not quite figured out how to make the Tokenish example work in Squeak. See attachment. Did not freeze on Mac with 10 Tokenish jumping. - Bert --- Juan Vuletich www.cuis-smalltalk.org https://github.com/Cuis-Smalltalk/Cuis-Smalltalk-Dev @JuanVuletich
-- Juan Vuletich www.cuis-smalltalk.org https://github.com/Cuis-Smalltalk/Cuis-Smalltalk-Dev @JuanVuletich