Is it safe to use rb_hash_delete() without having the GVL?

Ruby
1

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?

Thanks a lot.

2

Hi,

(2012/05/14 0:42), Iñaki Baz C. wrote:

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

3

2012/5/14 SASADA Koichi [email protected]:

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.

Thanks, I understand. However in my case I use Fixnums as keys in the
hash. I’ve done several tests and never crashes, maybe because Fixnum
objects are “untouchable”?

4

2012/5/14 Peter Z. [email protected]:

Fixnum instances are immutable and calling #hash should be safe on them.
However, point 2) stands: if two threads will access the hash
simultaneously,
that may and will lead to crashes.

Thanks. I’ll try to redesign my code then.

5

Iñaki Baz C. писал 14.05.2012 04:32:

hash. I’ve done several tests and never crashes, maybe because Fixnum
objects are “untouchable”?

Fixnum instances are immutable and calling #hash should be safe on
them.
However, point 2) stands: if two threads will access the hash
simultaneously,
that may and will lead to crashes.