Race condition on class copying when a thread reads a Threaded object provided from another thread #73

dktapps · 2021-11-28T19:56:41Z

When PTHREADS_INHERIT_NONE is used (or when a Threaded object is created using a class loaded after thread start), the class has to be copied on the fly by other threads when that Threaded object is read into said threads.

This is problematic because it may lead to races between the two threads, resulting in borked copies and/or segfaults.

This would have to be addressed by having the class copied to permanent storage when assigned to a Threaded member.

this is currently unfinished, and it will attempt to fire the autoloader for every class when INHERIT_ALL is used, which is not intended. the aim is to avoid class copying wherever possible, since copying classes is a source of stability issues. this change also allows sidestepping #73 for named classes.

we know already that copying classes on the fly for object sharing is racy (see #73), but this reduces the number of opportunities for a harmful race condition.

dktapps added the Threaded classes label Jul 25, 2022

dktapps mentioned this issue May 19, 2023

First look at preferring autoload over class copying #117

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Race condition on class copying when a thread reads a Threaded object provided from another thread #73

Race condition on class copying when a thread reads a Threaded object provided from another thread #73

dktapps commented Nov 28, 2021

Race condition on class copying when a thread reads a Threaded object provided from another thread #73

Race condition on class copying when a thread reads a Threaded object provided from another thread #73

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dktapps commented Nov 28, 2021