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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 |