normal	2017-05-20 18:47:14 +0900 (Sat, 20 May 2017)

  New Revision: 58812

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=58812

  Log:
    speed up IO#close with many threads
    
    Today, it increases IO#close performance with many threads:
    
      Execution time (sec)
      name            trunk   after
      vm_thread_close 4.276   3.018
    
      Speedup ratio: compare with the result of `trunk' (greater is better)
      name            after
      vm_thread_close 1.417
    
    This speedup comes because rb_notify_fd_close only scans threads
    inside rb_thread_io_blocking_region, not all threads in the VM.
    
    In the future, this type data structure may allow us to notify
    waiters of multiple FDs on a single thread (when using
    Fibers).
    
    * thread.c (struct waiting_fd): declare
      (rb_thread_io_blocking_region): use on-stack list waiter
      (rb_notify_fd_close): walk vm->waiting_fds instead
      (call_without_gvl): remove old field setting
      (th_init): ditto
    * vm_core.h (typedef struct rb_vm_struct): add waiting_fds list
    * (typedef struct rb_thread_struct): remove waiting_fd field
      (rb_vm_living_threads_init): initialize waiting_fds list
    
    I am now kicking myself for not thinking about this 3 years ago
    when I introduced ccan/list in [Feature #9632] to optimize this
    same function :<

  Modified files:
    trunk/thread.c
    trunk/vm.c
    trunk/vm_core.h
Index: vm.c
===================================================================
--- vm.c	(revision 58811)
+++ vm.c	(revision 58812)
@@ -2521,7 +2521,6 @@ th_init(rb_thread_t *th, VALUE self) https://github.com/ruby/ruby/blob/trunk/vm.c#L2521
     th->status = THREAD_RUNNABLE;
     th->errinfo = Qnil;
     th->last_status = Qnil;
-    th->waiting_fd = -1;
     th->root_svar = Qfalse;
     th->local_storage_recursive_hash = Qnil;
     th->local_storage_recursive_hash_for_trace = Qnil;
Index: vm_core.h
===================================================================
--- vm_core.h	(revision 58811)
+++ vm_core.h	(revision 58812)
@@ -490,6 +490,7 @@ typedef struct rb_vm_struct { https://github.com/ruby/ruby/blob/trunk/vm_core.h#L490
     struct rb_thread_struct *main_thread;
     struct rb_thread_struct *running_thread;
 
+    struct list_head waiting_fds; /* <=> struct waiting_fd */
     struct list_head living_threads;
     size_t living_thread_num;
     VALUE thgroup_default;
@@ -716,8 +717,6 @@ typedef struct rb_thread_struct { https://github.com/ruby/ruby/blob/trunk/vm_core.h#L717
     /* passing state */
     int state;
 
-    int waiting_fd;
-
     /* for rb_iterate */
     VALUE passed_block_handler;
 
@@ -1442,6 +1441,7 @@ void rb_thread_wakeup_timer_thread(void) https://github.com/ruby/ruby/blob/trunk/vm_core.h#L1441
 static inline void
 rb_vm_living_threads_init(rb_vm_t *vm)
 {
+    list_head_init(&vm->waiting_fds);
     list_head_init(&vm->living_threads);
     vm->living_thread_num = 0;
 }
Index: thread.c
===================================================================
--- thread.c	(revision 58811)
+++ thread.c	(revision 58812)
@@ -101,6 +101,12 @@ static int rb_threadptr_pending_interrup https://github.com/ruby/ruby/blob/trunk/thread.c#L101
 #define eTerminateSignal INT2FIX(1)
 static volatile int system_working = 1;
 
+struct waiting_fd {
+    struct list_node wfd_node; /* <=> vm.waiting_fds */
+    rb_thread_t *th;
+    int fd;
+};
+
 inline static void
 st_delete_wrap(st_table *table, st_data_t key)
 {
@@ -1316,7 +1322,6 @@ call_without_gvl(void *(*func)(void *), https://github.com/ruby/ruby/blob/trunk/thread.c#L1322
     rb_thread_t *th = GET_THREAD();
     int saved_errno = 0;
 
-    th->waiting_fd = -1;
     if (ubf == RUBY_UBF_IO || ubf == RUBY_UBF_PROCESS) {
 	ubf = ubf_select;
 	data2 = th;
@@ -1439,11 +1444,15 @@ VALUE https://github.com/ruby/ruby/blob/trunk/thread.c#L1444
 rb_thread_io_blocking_region(rb_blocking_function_t *func, void *data1, int fd)
 {
     volatile VALUE val = Qundef; /* shouldn't be used */
+    rb_vm_t *vm = GET_VM();
     rb_thread_t *th = GET_THREAD();
     volatile int saved_errno = 0;
     int state;
+    struct waiting_fd wfd;
 
-    th->waiting_fd = fd;
+    wfd.fd = fd;
+    wfd.th = th;
+    list_add(&vm->waiting_fds, &wfd.wfd_node);
 
     TH_PUSH_TAG(th);
     if ((state = EXEC_TAG()) == 0) {
@@ -1454,8 +1463,8 @@ rb_thread_io_blocking_region(rb_blocking https://github.com/ruby/ruby/blob/trunk/thread.c#L1463
     }
     TH_POP_TAG();
 
-    /* clear waiting_fd anytime */
-    th->waiting_fd = -1;
+    /* must be deleted before jump */
+    list_del(&wfd.wfd_node);
 
     if (state) {
 	TH_JUMP_TAG(th, state);
@@ -2196,12 +2205,13 @@ int https://github.com/ruby/ruby/blob/trunk/thread.c#L2205
 rb_notify_fd_close(int fd)
 {
     rb_vm_t *vm = GET_THREAD()->vm;
-    rb_thread_t *th = 0;
+    struct waiting_fd *wfd = 0;
     int busy;
 
     busy = 0;
-    list_for_each(&vm->living_threads, th, vmlt_node) {
-	if (th->waiting_fd == fd) {
+    list_for_each(&vm->waiting_fds, wfd, wfd_node) {
+	if (wfd->fd == fd) {
+	    rb_thread_t *th = wfd->th;
 	    VALUE err = th->vm->special_exceptions[ruby_error_stream_closed];
 	    rb_threadptr_pending_interrupt_enque(th, err);
 	    rb_threadptr_interrupt(th);

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