Author cykerway
Recipients barry, cykerway, methane, ncoghlan, terry.reedy, vstinner
Date 2018-08-06.09:58:27
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Message-id <1533549507.54.0.56676864532.issue34296@psf.upfronthosting.co.za>
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>   VM startup + `import site` are done in 10~20ms on common Linux machine.

>   While Python VM startup is not lightning fast, library import time is much slower than VM startup in many cases.

In my tests, a helloworld python script generally takes about 30-40 ms, while a similar helloworld bash script takes about 3-4 ms. Adding some common library imports (`os`, `sys`, etc.), then the python script's running time goes up to 60-70ms. I'm not sure how to compare this against bash because there are no library imports in bash. The 500ms (python) vs 50ms (bash) comparison is based on minimal implementations of the same simple job and meant to reflect the minimal amount of time needed for such a job in different languages. While it doesn't cover everything and may not even be fair enough, the result does match that of the helloworld test (10 times faster/slower). Plus, in your linked post, it shows importing pipenv takes about 700ms. Therefore I believe some hundreds of milliseconds are necessary for such scripts that do a simple but meaningful job.

I understand many things can happen while importing a library. But for a specific program, its imports are usually fixed and very much likely the same between runs. That's why I believe a zygote/fork/snapshot feature would still be helpful to help avoid the startup delay.

Finally, for simple and quick user scrips, the 30-40 ms startup time without any import statements may not be a huge problem, but it's still tangible and makes the program feel not that sleek.
History
Date User Action Args
2018-08-06 09:58:27cykerwaysetrecipients: + cykerway, barry, terry.reedy, ncoghlan, vstinner, methane
2018-08-06 09:58:27cykerwaysetmessageid: <1533549507.54.0.56676864532.issue34296@psf.upfronthosting.co.za>
2018-08-06 09:58:27cykerwaylinkissue34296 messages
2018-08-06 09:58:27cykerwaycreate