Doc #63842 [Opn]: Infinite loop in example code
| From: | dean at ovts dot com dot au | Date: | Thu, 03 Jan 2013 15:05:11 +0000 |
| Subject: | Doc #63842 [Opn]: Infinite loop in example code | ||
| References: | 1 | Groups: | php.doc.bugs |
| Request: | Send a blank email to doc-bugs+get-9346@lists.php.net to get a copy of this message | ||
Edit report at https://bugs.php.net/bug.php?id=63842&edit=1
ID: 63842
User updated by: dean at ovts dot com dot au
Reported by: dean at ovts dot com dot au
Summary: Infinite loop in example code
Status: Open
Type: Documentation Problem
Package: Documentation problem
PHP Version: Irrelevant
Block user comment: N
Private report: N
New Comment:
That would certainly fix the inifinite loop problem.
I'm not clear on why you'd need to wait 100ms (or some other arbitrary amount of time)
before calling curl_multi_exec again... this just seems like bad design to me (even if the libcurl
docs recommend it). How many times might you end up doing this 100ms sleep? The whole point of
curl_multi_select is to sleep exactly the minimum amount, and wake up as soon as some curl operation
is ready to continue.
What would happen if you simply ignored the return value of curl_multi_select, and did this:
while (curl_multi_exec($mh, $active) === CURLM_CALL_MULTI_PERFORM);
do
{
curl_multi_select($curlMH);
while (curl_multi_exec($curlMH, $active) === CURLM_CALL_MULTI_PERFORM);
} while ($active);
(Also, do we need to break if curl_multi_exec doesn't return CURLM_OK, or can we just keep
going until $active is false, as I've done above? What would it mean if $active were true, but
the return value wasn't CURLM_OK?)
Previous Comments:
------------------------------------------------------------------------
[2012-12-31 23:04:18] mail+php at requinix dot net
curl_multi_init()'s example has the same problem. Given the history of the
underlying bug (see bug #63411, bug #61141) I'm hesitant to just go in and
submit a change.
In the comments for 61141 are two code bits that should work, the preferred one
(from pierrick) being
while ($active && $mrc == CURLM_OK) {
if (curl_multi_select($mh) == -1) usleep(100);
do { $mrc = curl_multi_exec($mh, $active); }
while ($mrc == CURLM_CALL_MULTI_PERFORM);
}
------------------------------------------------------------------------
[2012-12-24 06:48:36] dean at ovts dot com dot au
Description:
------------
---
From manual page: http://www.php.net/function.curl-multi-exec
---
I think there's a bug in the sample code.
If curl_multi_select() returns -1, then the while{} loop just keeps calling it until it returns
something else.
So if repeated calles to curl_multi_select() can return -1 indefinitely (and the comments on the
manual page for that function suggest it can), then the example code will just go into an infinite
loop.
------------------------------------------------------------------------
--
Edit this bug report at https://bugs.php.net/bug.php?id=63842&edit=1