[tarantool-patches] Re: [PATCH] Output of fiber.info will contain only non-idle fibers

[Konstantin Osipov]

* Maria K <marianneliash at gmail.com> [19/07/23 21:01]:
> The output used to be too cluttered due to idle ones.
> 
> Closes #4235

@kyukhin, first, please I don't get how does this get scheduled to a
milestone? How does this follow triage guidelines? 

Please don't schedule anything that is not a priority, even if
it's a noob issue, since it takes time of everyone involved.

fiber.info() already doesn't show anything from cord->dead list.
Fibers which are stuck in a pool are performing application-level
code, even if it's a built in pool, so contribute valuable
information to fiber.info() output. Besides, it's always easy to
filter out any class of fibers with luafun.

Finally, there are other types of pools -- an application-level pool
in Lua will have lots of idle fibers in it. 

In other words, this is an partial fix of a raw feature
request.

Tarantool instrumentation sucks, but it doesn't mean it should be
patched by quick hacks here and there.

A nice and general solution would be to compress mostly identical
fiber.info() entries. But I guess it's not a noob task.

> ---
>  src/lib/core/fiber.c      |  3 ++-
>  src/lib/core/fiber.h      | 10 ++++++++++
>  src/lib/core/fiber_pool.c |  2 ++
>  3 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/src/lib/core/fiber.c b/src/lib/core/fiber.c
> index ce90f930c..b1d7a5be2 100644
> --- a/src/lib/core/fiber.c
> +++ b/src/lib/core/fiber.c
> @@ -1411,7 +1411,8 @@ int fiber_stat(fiber_stat_cb cb, void *cb_ctx)
>   struct cord *cord = cord();
>   int res;
>   rlist_foreach_entry(fiber, &cord->alive, link) {
> - res = cb(fiber, cb_ctx);
> + if (!fiber_is_idle(fiber))
> + res = cb(fiber, cb_ctx);
>   if (res != 0)
>   return res;
>   }
> diff --git a/src/lib/core/fiber.h b/src/lib/core/fiber.h
> index fb168e25e..d05132a8d 100644
> --- a/src/lib/core/fiber.h
> +++ b/src/lib/core/fiber.h
> @@ -97,6 +97,10 @@ enum {
>   * This flag is set when fiber uses custom stack size.
>   */
>   FIBER_CUSTOM_STACK = 1 << 5,
> + /*
> + *
> + */
> + FIBER_IS_IDLE = 1 << 6,
>   FIBER_DEFAULT_FLAGS = FIBER_IS_CANCELLABLE
>  };
> 
> @@ -620,6 +624,12 @@ fiber_is_dead(struct fiber *f)
>   return f->flags & FIBER_IS_DEAD;
>  }
> 
> +static inline bool
> +fiber_is_idle(struct fiber *f)
> +{
> + return f->flags & FIBER_IS_IDLE;
> +}
> +
>  typedef int (*fiber_stat_cb)(struct fiber *f, void *ctx);
> 
>  int
> diff --git a/src/lib/core/fiber_pool.c b/src/lib/core/fiber_pool.c
> index 77f89c9fa..c04141e63 100644
> --- a/src/lib/core/fiber_pool.c
> +++ b/src/lib/core/fiber_pool.c
> @@ -72,8 +72,10 @@ restart:
>   * Add the fiber to the front of the list, so that
>   * it is most likely to get scheduled again.
>   */
> + f->flags |= FIBER_IS_IDLE;
>   rlist_add_entry(&pool->idle, fiber(), state);
>   fiber_yield();
> + f->flags &= ~FIBER_IS_IDLE;
>   goto restart;
>   }
>   pool->size--;
> -- 
> 2.21.0

-- 
Konstantin Osipov, Moscow, Russia