view src/os/unix/ngx_thread_id.c @ 8751:555533169506

HTTP/2: fixed "task already active" with sendfile in threads. With sendfile in threads, "task already active" alerts might appear in logs if a write event happens on the main HTTP/2 connection, triggering a sendfile in threads while another thread operation is already running. Observed with "aio threads; aio_write on; sendfile on;" and with thread event handlers modified to post a write event to the main HTTP/2 connection (though can happen without any modifications). Similarly, sendfile() with AIO preloading on FreeBSD can trigger duplicate aio operation, resulting in "second aio post" alerts. This is, however, harder to reproduce, especially on modern FreeBSD systems, since sendfile() usually does not return EBUSY. Fix is to avoid starting a sendfile operation if other thread operation is active by checking r->aio in the thread handler (and, similarly, in aio preload handler). The added check also makes duplicate calls protection redundant, so it is removed.
author Maxim Dounin <mdounin@mdounin.ru>
date Thu, 25 Nov 2021 22:02:05 +0300
parents 466bd63b63d1
children
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_thread_pool.h>


#if (NGX_LINUX)

/*
 * Linux thread id is a pid of thread created by clone(2),
 * glibc does not provide a wrapper for gettid().
 */

ngx_tid_t
ngx_thread_tid(void)
{
    return syscall(SYS_gettid);
}

#elif (NGX_FREEBSD) && (__FreeBSD_version >= 900031)

#include <pthread_np.h>

ngx_tid_t
ngx_thread_tid(void)
{
    return pthread_getthreadid_np();
}

#elif (NGX_DARWIN)

/*
 * MacOSX thread has two thread ids:
 *
 * 1) MacOSX 10.6 (Snow Leoprad) has pthread_threadid_np() returning
 *    an uint64_t value, which is obtained using the __thread_selfid()
 *    syscall.  It is a number above 300,000.
 */

ngx_tid_t
ngx_thread_tid(void)
{
    uint64_t  tid;

    (void) pthread_threadid_np(NULL, &tid);
    return tid;
}

/*
 * 2) Kernel thread mach_port_t returned by pthread_mach_thread_np().
 *    It is a number in range 100-100,000.
 *
 * return pthread_mach_thread_np(pthread_self());
 */

#else

ngx_tid_t
ngx_thread_tid(void)
{
    return (uint64_t) (uintptr_t) pthread_self();
}

#endif