Issue #13552 has been updated by ko1 (Koichi Sasada).



> https://80x24.org/spew/20170519034419.GA29820@whir/raw

Thank you. Adding `const` helps us to recognize.

```
PACKED_STRUCT_UNALIGNED(struct rb_queue {
    struct list_head waitq;
    const VALUE que;
    int num_waiting;
});
```

> I'm not sure how this helps performance, however. The Arrays
> are constantly changing with push/pop and RGenGC works best for
> stable (unchanging) objects (correct?)

Sorry, I can't understand your question.
Could you give me your question in other words?

> Also, does setting RUBY_TYPED_WB_PROTECTED make sense for
> rb_condvar and rb_mutex_t? They store no Ruby objects and
> have no dmark callback.

Yes, please. not wb protected objects become roots for all of minor gc.
No write is the best wb protected object.


----------------------------------------
Feature #13552: [PATCH 0/2] reimplement ConditionVariable, Queue, SizedQueue using ccan/list
https://bugs.ruby-lang.org/issues/13552#change-64908

* Author: normalperson (Eric Wong)
* Status: Assigned
* Priority: Normal
* Assignee: normalperson (Eric Wong)
* Target version: 2.5
----------------------------------------
```
The performance improvement increases as the number of waiters
increases, due to avoiding the O(n) behavior of rb_ary_delete on
the waiting thread.  Uncontended queues and condition variables
performance is not altered significantly.

Function entry cost is slightly increased for ConditionVariable,
since the data pointer is separately allocated and not embedded
into the RVALUE slot.

name                  |trunk  |built
----------------------|------:|------:
vm_thread_condvar1    |  0.858|  0.858
vm_thread_condvar2    |  1.003|  0.804
vm_thread_queue       |  0.131|  0.129
vm_thread_sized_queue |  0.265|  0.251
vm_thread_sized_queue2|  0.892|  0.859
vm_thread_sized_queue3|  0.879|  0.845
vm_thread_sized_queue4|  0.599|  0.486

Speedup ratio: compare with the result of `trunk' (greater is better)

name                  |built
----------------------|------:
vm_thread_condvar1    |  0.999
vm_thread_condvar2    |  1.246
vm_thread_queue       |  1.020
vm_thread_sized_queue |  1.057
vm_thread_sized_queue2|  1.039
vm_thread_sized_queue3|  1.041
vm_thread_sized_queue4|  1.233
```


---Files--------------------------------
0001-thread_sync.c-rename-mutex_waiter-struct-to-sync_wai.patch (1.63 KB)
0002-thread_sync.c-rewrite-the-rest-using-using-ccan-list.patch (21.3 KB)


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