libglusterfs: Name threads on creation

Set names to threads on creation for easier
debugging.

Output of top -H -p <PID-OF-GLUSTERFSD>
Before:
19773 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19774 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19775 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19776 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19777 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19778 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19779 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19780 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19781 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19782 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19783 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19784 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19785 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.01 glusterfsd
19786 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.01 glusterfsd
19787 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.01 glusterfsd
19789 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19790 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
25178 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
 5398 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
 7881 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd

After:
19773 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19774 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glustertimer
19775 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterfsd
19776 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glustermemsweep
19777 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glustersproc0
19778 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glustersproc1
19779 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterepoll0
19780 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusteridxwrker
19781 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusteriotwr0
19782 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterbrssign
19783 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterbrswrker
19784 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterclogecon
19785 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.01 glusterclogd0
19786 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.01 glusterclogd1
19787 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.01 glusterclogd2
19789 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterposixjan
19790 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterposixfsy
25178 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterepoll1
 5398 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterepoll2
 7881 root      20   0 1301.3m  12.6m   8.4m S  0.0  0.1   0:00.00 glusterposixhc

Change-Id: Id5f333755c1ba168a2ffaa4fce6e71c375e10703
BUG: 1254002
Updates: #271
Signed-off-by: Raghavendra Talur <rtalur@redhat.com>
Reviewed-on: https://review.gluster.org/11926
Reviewed-by: Prashanth Pai <ppai@redhat.com>
Smoke: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Niels de Vos <ndevos@redhat.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>

1 files changed, 104 insertions, 0 deletions

diff --git a/doc/developer-guide/thread-naming.md b/doc/developer-guide/thread-naming.md
new file mode 100644
index 00000000000..204cd7681b4
--- /dev/null
+++ b/doc/developer-guide/thread-naming.md
@@ -0,0 +1,104 @@
+Thread Naming
+================
+Gluster processes spawn many threads; some threads are created by libglusterfs
+library, while others are created by xlators. When gfapi library is used in an
+application, some threads belong to the application and some are spawned by
+gluster libraries. We also have features where n number of threads are spawned
+to act as worker threads for same operation.
+
+In all the above cases, it is useful to be able to determine the list of threads
+that exist in runtime. Naming threads when you create them is the easiest way to
+provide that information to kernel so that it can then be queried by any means.
+
+How to name threads
+-------------------
+We have two wrapper functions in libglusterfs for creating threads. They take
+name as an argument and set thread name after its creation.
+
+```C
+gf_thread_create (pthread_t *thread, const pthread_attr_t *attr,
+                  void *(*start_routine)(void *), void *arg, const char *name)
+```
+
+```C
+gf_thread_create_detached (pthread_t *thread,
+                           void *(*start_routine)(void *), void *arg,
+                           const char *name)
+```
+
+As max name length for a thread in POSIX is only 16 characters including the
+'\0' character, you have to be a little creative with naming. Also, it is
+important that all Gluster threads have common prefix. Considering these
+conditions, we have "gluster" as prefix for all the threads created by these
+wrapper functions. It is responsibility of the owner of thread to provide the
+suffix part of the name. It does not have to be a descriptive name, as it has
+only 8 letters to work with. However, it should be unique enough such that it
+can be matched with a table which describes it.
+
+If n number of threads are spwaned to perform same function, it is must that the
+threads are numbered.
+
+Table of thread names
+---------------------
+Thread names don't have to be a descriptive; however, it should be unique enough
+such that it can be matched with a table below without ambiguity.
+
+- bdaio    - block device aio
+- brfsscan - bit rot fs scanner
+- brhevent - bit rot event handler
+- brmon    - bit rot monitor
+- brosign  - bit rot one shot signer
+- brpobj   - bit rot object processor
+- brsproc  - bit rot scrubber
+- brssign  - bit rot stub signer
+- brswrker - bit rot worker
+- clogc    - changelog consumer
+- clogcbki - changelog callback invoker
+- clogd    - changelog dispatcher
+- clogecon - changelog reverse connection
+- clogfsyn - changelog fsync
+- cloghcon - changelog history consumer
+- clogjan  - changelog janitor
+- clogpoll - changelog poller
+- clogproc - changelog process
+- clogro   - changelog rollover
+- ctrcomp  - change time recorder compaction
+- dhtdf    - dht defrag task
+- dhtdg    - dht defrag start
+- dhtfcnt  - dht rebalance file counter
+- ecshd    - ec heal daemon
+- epollN   -  epoll thread
+- fdlwrker - fdl worker
+- fusenoti - fuse notify
+- fuseproc - fuse main thread
+- gdhooks  - glusterd hooks
+- glfspoll -  gfapi poller thread
+- idxwrker - index worker
+- iosdump  - io stats dump
+- iotwr    - io thread worker
+- jbrflush - jbr flush
+- leasercl - lease recall
+- memsweep - sweeper thread for mem pools
+- nfsauth  - nfs auth
+- nfsnsm   - nfs nsm
+- nfsudp   - nfs udp mount
+- nlmmon   - nfs nlm/nsm mon
+- posixaio - posix aio
+- posixfsy - posix fsync
+- posixhc  - posix heal
+- posixjan - posix janitor
+- quiesce  - quiesce dequeue
+- rdmaAsyn - rdma async event handler
+- rdmaehan - rdma completion handler
+- rdmarcom - rdma receive completion handler
+- rdmascom - rdma send completion handler
+- rpcsvcrh - rpcsvc request handler
+- scleanup - socket cleanup
+- shdheal  - self heal daemon
+- sigwait  -  glusterfsd sigwaiter
+- spoller  - socket poller
+- sprocN   - syncop worker thread
+- tbfclock - token bucket filter token generator thread
+- tierfixl - tier fix layout
+- timer    - timer thread
+- upreaper - upcall reaper