qt_wait4(3)

💖 qt_wait4 — bestie edition 💖

okay so this is a page from the libqthread manual, section 3, and it's all about qt_wait4 🫶

✨ NAME ✨

qt_wait4 — wait for process termination 👀💤

🌸 SYNOPSIS 🌸

#include <qthread/qt_syscalls.h>

int
qt_wait4 (pid_t pid,
          int *stat_loc,
          int options,
          struct rusage *rusage);

🦋 DESCRIPTION 🦋

so like, this is a wrapper around the standard wait4() system call function 💅 instead of just raw-dogging that blocking system call directly, the operation gets enqueued into the internal system call queue to be handled. no cap, that's the whole move. 🎀

the system call queue is literally the way you do blocking system calls without impeding parallel computation ✨ operations get enqueued in an internal queue, and that queue is serviced by a dynamic number of dedicated system call threads. iconic behaviour honestly.

that set of threads is capped at a user-configurable limit, and you specify it with the QT_MAX_IO_WORKERS environment variable at initialization time ⏰ don't forget the timing bestie, it matters.

when there are no more operations in the system call queue, these workers are persistent for a configurable amount of time — specified with the QT_IO_TIMEOUT environment variable at initialization time — before they exit 🚪💨 and the reason for that lil grace period? it's to reduce the overhead involved in scaling up the number of worker threads to respond to newly enqueued system calls. so they just kinda hang around for a bit instead of ghosting immediately. main character energy, truly. 👑

ngl the "at initialization time" bit is doing a LOT of heavy lifting here — both QT_MAX_IO_WORKERS and QT_IO_TIMEOUT are read when things start up, so setting them later is not the vibe 💀

🌈 SEE ALSO 🌈

• wait4(2)
• qt_accept(3)
• qt_connect(3)
• qt_poll(3)
• qt_pread(3)
• qt_pwrite(3)
• qt_read(3)
• qt_select(3)
• qt_system(3)
• qt_write(3)

and that's the whole page, bestie 🥹 this was libqthread, AUGUST 2012, qt_wait4(3) — literally iconic, obsessed, periodt 💅✨🎀🦋🌸💖