From: SASADA Koichi <ko1@...>
Date: 2012-05-14T08:55:21+09:00
Subject: Re: [C exten] Is it safe to use rb_hash_delete() without having the GVL?

Hi,

(2012/05/14 0:42), I単aki Baz Castillo wrote:
> Hi, my code is a C event loop that runs without the GVL (so other Ruby
> 1.9.3 threads can take the control) and when an event occurs it get
> the GVL and executed a user provided Ruby block/proc.
> 
> Prior to calling rb_thread_call_with_gvl(), my code removes an element
> from a Ruby hash by using rb_hash_delete(). This is, such an operation
> is done from a thread which has not the GVL, so it could be dangerous.
> However I get no errors at all. If I run more Ruby code without having
> the GVL then of course I get critical errors, but that does not occur
> if I just use rb_hash_delete().
> 
> So, is it safe to use rb_hash_delete() without having the GVL?

I believe it is dangerous.

Because:

(1) rb_hash_delete() can call Ruby's #hash method for each elements.
(2) If another thread access to the hash simultaneously, it will be crash.

Regards,
Koichi

-- 
// SASADA Koichi at atdot dot net