From: Johannes Sixt <j.sixt@viscovery.net>
Date: Tue, 11 Dec 2007 17:02:35 GMT
Subject: Re: [PATCH 2/2] pack-objects: fix threaded load balancing
Message-ID: <475EC2AB.60702@viscovery.net>
In-Reply-To: <alpine.LFD.0.99999.0712080000120.555@xanadu.home>

Nicolas Pitre schrieb:
> @@ -1612,10 +1620,10 @@ static void *threaded_find_deltas(void *arg)
>  		pthread_mutex_lock(&data_ready);
>  		pthread_mutex_unlock(&data_request);
>  
> -		if (!me->list_size)
> +		if (!me->remaining)
>  			return NULL;
>  
> -		find_deltas(me->list, me->list_size,
> +		find_deltas(me->list, &me->remaining,
>  			    me->window, me->depth, me->processed);
>  	}
>  }

This hunk caught my attention. &data_ready is locked, but not released in
this function.

Looking more closely at the code surrounding this hunk, it seems that the
lock is released in a *different* thread than the one that locked it. This
works on Linux, but is not portable. We will have to use condition variables
like every one else does in a producer-consumer-like scenario.

-- Hannes