ID: 47487
User updated by: basant dot kukreja at gmail dot com
Reported By: basant dot kukreja at gmail dot com
Status: Open
Bug Type: Performance problem
Operating System: Solaris 10
PHP Version: 5.2.9RC3
New Comment:
Sorry, file name was missing from the patch :
--- a/php-5.2.9RC3/main/streams/streams.c Sun Feb 22 19:57:30
2009 -0800
+++ b/php-5.2.9RC3/main/streams/streams.c Tue Feb 24 00:50:21
2009 -0800
@@ -1251,6 +1253,11 @@
* 2K). */
if (php_stream_stat(src, &ssbuf) == 0 && ssbuf.sb.st_size > 0)
{
max_len = ssbuf.sb.st_size + step;
+ if (max_len > src->readbuflen) {
+ src->readbuflen = max_len;
+ src->readbuf = perealloc(src->readbuf,
src->readbuflen,
+
src->is_persistent);
+ }
} else {
max_len = step;
}
Previous Comments:
------------------------------------------------------------------------
[2009-02-24 08:59:45] basant dot kukreja at gmail dot com
There might be several possible way to fix it. Here is one alternative
which requires more memory but avoid includes :
@@ -1251,6 +1253,11 @@
* 2K). */
if (php_stream_stat(src, &ssbuf) == 0 && ssbuf.sb.st_size > 0)
{
max_len = ssbuf.sb.st_size + step;
+ if (max_len > src->readbuflen) {
+ src->readbuflen = max_len;
+ src->readbuf = perealloc(src->readbuf,
src->readbuflen,
+
src->is_persistent);
+ }
} else {
max_len = step;
}
--------------------------------
The above patch though have single alloc but still require large
memory allocation. Before this patch too, large memory is allocated
but by several folds.
Before PR http://bugs.php.net/bug.php?id=44607
was fixed, php only required 8KB memory at a time and no reallocs
happened.
------------------------------------------------------------------------
[2009-02-24 08:52:57] basant dot kukreja at gmail dot com
Description:
------------
After bug 44607 is fixed, php_stream_fill_read_buffer does many
reallocs for
medium to large file (e.g 60KB)
Before the bug 44607 was fixed, php_stream_fill_read_buffer returns
after
single read so there was no reallocs. But after the fix, it keeps
reading
until the entire file is read.
Reproduce code:
---------------
If we add a printf in php_stream_fill_read_buffer function like :
while (stream->writepos - stream->readpos < (off_t)size) {
size_t justread = 0;
size_t toread;
/* grow the buffer if required
* TODO: this can fail for persistent streams */
if (stream->readbuflen - stream->writepos <
stream->chunk_size) {
stream->readbuflen += stream->chunk_size;
fprintf(stderr, "php_stream_fill_read_buffer
:reallocating %d\n",
stream->readbuflen);
stream->readbuf = perealloc(stream->readbuf,
stream->readbuflen,
stream->is_persistent);
}
Then for a php script which includes 60KB html file, following
is printed.
stderr: php_stream_fill_read_buffer :reallocating 8192
stderr: php_stream_fill_read_buffer :reallocating 16384
stderr: php_stream_fill_read_buffer :reallocating 24576
stderr: php_stream_fill_read_buffer :reallocating 32768
stderr: php_stream_fill_read_buffer :reallocating 40960
stderr: php_stream_fill_read_buffer :reallocating 49152
stderr: php_stream_fill_read_buffer :reallocating 57344
Expected result:
----------------
Less number of memcpy. Because of the reallocs, huge amount of memcpy
happens. This happened after php-5.2.6.
http://bugs.php.net/bug.php?id=44607
Actual result:
--------------
Degrade in performance.
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/?id=47487&edit=1
