Run prefilter/postfilter shells via single-threaded worker processes - #389
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e-n-f wants to merge 1 commit into
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Run prefilter/postfilter shells via single-threaded worker processes#389e-n-f wants to merge 1 commit into
e-n-f wants to merge 1 commit into
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Forking and waitpid()-ing for the -C/-c shell filters used to happen directly in the multi-threaded tiling threads, which made fork() expensive (full COW of the parent's address space) and unsafe (other threads could hold libc/malloc locks at fork time). Now we pre-fork a small pool of single-threaded worker processes once, before any tiling or reader threads are spawned, and the tiling threads ask a worker to fork+exec the shell child on their behalf, receiving the input/output pipe fds back via SCM_RIGHTS. The fork() and waitpid() happen entirely inside the single-threaded worker, where they are cheap and only block that worker. Co-authored-by: Cursor <cursoragent@cursor.com>
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Forking and waitpid()-ing for the -C/-c shell filters used to happen directly in the multi-threaded tiling threads, which made fork() expensive (full COW of the parent's address space) and unsafe (other threads could hold libc/malloc locks at fork time). Now we pre-fork a small pool of single-threaded worker processes once, before any tiling or reader threads are spawned, and the tiling threads ask a worker to fork+exec the shell child on their behalf, receiving the input/output pipe fds back via SCM_RIGHTS. The fork() and waitpid() happen entirely inside the single-threaded worker, where they are cheap and only block that worker.