Threaded IO: set thread name for redis-server

Set thread name for each thread of redis-server, this helps us to
monitor the utilization and optimise the performance.

And suggested-by Salvatore, implement this feature for multi
platforms. Currently support linux and bsd, ignore other OS.

An exmaple on Linux:
 # top -d 5 -p `pidof redis-server ` -H

    PID USER      PR  NI    VIRT    RES    SHR S %CPU %MEM     TIME+ COMMAND
3682671 root      20   0  227744   8248   3836 R 99.2  0.0   0:19.53 redis-server
3682677 root      20   0  227744   8248   3836 S 26.4  0.0   0:04.15 io_thd_3
3682675 root      20   0  227744   8248   3836 S 23.6  0.0   0:03.98 io_thd_1
3682676 root      20   0  227744   8248   3836 S 23.6  0.0   0:03.97 io_thd_2
3682672 root      20   0  227744   8248   3836 S  0.2  0.0   0:00.02 bio_close_file
3682673 root      20   0  227744   8248   3836 S  0.2  0.0   0:00.02 bio_aof_fsync
3682674 root      20   0  227744   8248   3836 S  0.0  0.0   0:00.00 bio_lazy_free
3682678 root      20   0  227744   8248   3836 S  0.0  0.0   0:00.00 jemalloc_bg_thd
3682682 root      20   0  227744   8248   3836 S  0.0  0.0   0:00.00 jemalloc_bg_thd
3682683 root      20   0  227744   8248   3836 S  0.0  0.0   0:00.00 jemalloc_bg_thd
3682684 root      20   0  227744   8248   3836 S  0.0  0.0   0:00.00 jemalloc_bg_thd
3682685 root      20   0  227744   8248   3836 S  0.0  0.0   0:00.00 jemalloc_bg_thd
3682687 root      20   0  227744   8248   3836 S  0.0  0.0   0:00.00 jemalloc_bg_thd

Another exmaple on FreeBSD-12.1:
  PID USERNAME    PRI NICE   SIZE    RES STATE    C   TIME    WCPU COMMAND
 5212 root        100    0    48M  7280K CPU2     2   0:26  99.52% redis-server{redis-server}
 5212 root         38    0    48M  7280K umtxn    4   0:06  26.94% redis-server{io_thd_3}
 5212 root         36    0    48M  7280K umtxn    6   0:06  26.84% redis-server{io_thd_1}
 5212 root         39    0    48M  7280K umtxn    1   0:06  25.30% redis-server{io_thd_2}
 5212 root         20    0    48M  7280K uwait    3   0:00   0.00% redis-server{redis-server}
 5212 root         21    0    48M  7280K uwait    2   0:00   0.00% redis-server{bio_close_file}
 5212 root         21    0    48M  7280K uwait    3   0:00   0.00% redis-server{bio_aof_fsync}
 5212 root         21    0    48M  7280K uwait    0   0:00   0.00% redis-server{bio_lazy_free}

Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>

src/bio.c

@@ -154,6 +154,18 @@ void *bioProcessBackgroundJobs(void *arg) {
         return NULL;
     }
 
+    switch (type) {
+    case BIO_CLOSE_FILE:
+        redis_set_thread_title("bio_close_file");
+        break;
+    case BIO_AOF_FSYNC:
+        redis_set_thread_title("bio_aof_fsync");
+        break;
+    case BIO_LAZY_FREE:
+        redis_set_thread_title("bio_lazy_free");
+        break;
+    }
+
     /* Make the thread killable at any time, so that bioKillThreads()
      * can work reliably. */
     pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);

src/config.h

@@ -226,4 +226,16 @@ void setproctitle(const char *fmt, ...);
 #define USE_ALIGNED_ACCESS
 #endif
 
+/* Define for redis_set_thread_title */
+#ifdef __linux__
+#define redis_set_thread_title(name) pthread_setname_np(pthread_self(), name)
+#else
+#if (defined __NetBSD__ || defined __FreeBSD__ || defined __OpenBSD__)
+#include <pthread_np.h>
+#define redis_set_thread_title(name) pthread_set_name_np(pthread_self(), name)
+#else
+#define redis_set_thread_title(name)
+#endif
+#endif
+
 #endif

src/networking.c

@@ -2821,6 +2821,10 @@ void *IOThreadMain(void *myid) {
     /* The ID is the thread number (from 0 to server.iothreads_num-1), and is
      * used by the thread to just manipulate a single sub-array of clients. */
     long id = (unsigned long)myid;
+    char thdname[16];
+
+    snprintf(thdname, sizeof(thdname), "io_thd_%ld", id);
+    redis_set_thread_title(thdname);
 
     while(1) {
         /* Wait for start */