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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

This is a wrapper around the standard wait4() system call function. Instead of executing this blocking system call directly, the operation is enqueued in the internal system call queue to be handled.

The system call queue provides a way to perform blocking system calls without impeding parallel computation. Operations are enqueued in an internal queue which is serviced by a dynamic number of dedicated system call threads. This set of threads is capped at a user-configurable limit, specified with the QT_MAX_IO_WORKERS environment variable at initialization time. 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. This is to reduce the overhead involved in scaling up the number of worker threads to respond to newly enqueued system calls.

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)


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