[Python-Dev] GIL behaviour under Windows (original) (raw)

John Arbash Meinel john.arbash.meinel at gmail.com
Wed Oct 21 19:42:51 CEST 2009

Antoine Pitrou wrote:

Sturla Molden <sturla molden.no> writes:

It does not crash the interpreter, but it seems it can deadlock. Kristján sent me a patch which I applied and is supposed to fix this. Anyway, thanks for the numbers. The GIL does seem to fare a bit better (zero latency with the Pi calculation in the background) than under Linux, although it may be caused by the limited resolution of time.time() under Windows. Regards Antoine.

You can use time.clock() instead to get <15ms resolution. Changing all instances of 'time.time' to 'time.clock' gives me this result:

(2-core machine, python 2.6.2)

$ py ccbench.py --- Throughput ---

Pi calculation (Python)

threads=1: 675 iterations/s. threads=2: 388 ( 57 %) threads=3: 374 ( 55 %) threads=4: 445 ( 65 %)

regular expression (C)

threads=1: 588 iterations/s. threads=2: 519 ( 88 %) threads=3: 511 ( 86 %) threads=4: 513 ( 87 %)

bz2 compression (C)

threads=1: 536 iterations/s. threads=2: 949 ( 176 %) threads=3: 900 ( 167 %) threads=4: 927 ( 172 %)

--- Latency ---

Background CPU task: Pi calculation (Python)

CPU threads=0: 24727 ms. (std dev: 0 ms.) CPU threads=1: 27930 ms. (std dev: 0 ms.) CPU threads=2: 31029 ms. (std dev: 0 ms.) CPU threads=3: 34170 ms. (std dev: 0 ms.) CPU threads=4: 37292 ms. (std dev: 0 ms.)

Background CPU task: regular expression (C)

CPU threads=0: 40454 ms. (std dev: 0 ms.) CPU threads=1: 43674 ms. (std dev: 21 ms.) CPU threads=2: 47100 ms. (std dev: 165 ms.) CPU threads=3: 50441 ms. (std dev: 304 ms.) CPU threads=4: 53707 ms. (std dev: 377 ms.)

Background CPU task: bz2 compression (C)

CPU threads=0: 56138 ms. (std dev: 0 ms.) CPU threads=1: 59332 ms. (std dev: 0 ms.) CPU threads=2: 62436 ms. (std dev: 0 ms.) CPU threads=3: 66130 ms. (std dev: 0 ms.) CPU threads=4: 69859 ms. (std dev: 0 ms.)

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