On 13 May 2013, at 22:04, Christophe JAILLET <[email protected]>
wrote:
> trying to reduce httpd memory usage, I've worked on ap_rgetline_core in
> protocol.c.
>
> This function gets a line of protocol input.
>
> To do so, :
> - it processes the apr_bucket_brigade it is given in parameter, one bucket
> at a time
> - for the common case, it allocates memory to store the data from the
> bucket, with a minimum on 80 bytes, to try to avoid other memory allocations,
> should there be other buckets
> - in case of several buckets and 80 bytes was not enough, it doubles the
> memory allocated and copy data in the new buffer
>
>
> Why is this minimum of 80 bytes there ?
>
> As stated in the comment, we assume the common case : only 1 bucket.
> According to my testing, with a basic configuration and a simple request,
> this is the case.
>
>
> So, I suggest,
> * either to simply remove the test line 293 in protocol.c and the use of
> MIN_LINE_ALLOC
> if (current_alloc < MIN_LINE_ALLOC) {
> current_alloc = MIN_LINE_ALLOC;
> }
> The already in place mechanism will grow the buffer if needed
>
> * or, if you prefer to over allocate in case of several buckets, turn it
> into:
> if (APR_BUCKET_NEXT(e) != APR_BRIGADE_SENTINEL(bb)) {
> if (current_alloc < MIN_LINE_ALLOC) {
> current_alloc = MIN_LINE_ALLOC;
> }
> }
> to save memory when we know we can.
>
>
> Personally, I prefer the first version and drop the test and the use of
> MIN_LINE_ALLOC.
+1.
Regards,
Graham
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