php / php/php-src

Resource ID space overflow: Better approach to incremental resource id assignment

Open
#19,253 3 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Bug Status: Needs Triage
Dominant language
C
Stars
40.4k
Forks
8.1k
Avg merge
2d 13h
Merged PRs (30d)
96

Description

Description

We have the following simple code that runs in a daemon which is expected to to run very long time. However it looks like a new resource id is assigned every time this runs. And this runs a lot as we write to a ramdisk.
The following code:

61
62 file_put_contents("/dev/shm/somefile.txt", $data, LOCK_EX);
63 

Resulted in this output:

PHP Fatal error:  Resource ID space overflow in cache.class.php on line 62

But I expected this output instead:

No errors.
I understand that file_put_contents() creates a temporary file resource on each run and probably it's reaching  PHP_INT_MAX to cause this fatal error.
There is only one function get_resource_id() to guess and deal with this issue. Workaround is to keep file handles active during execution.

A)
PHP can handle this by resetting it back to 0 and adding a check to compare it to existing active resources(to avoid conflict) If this is not feasible, I could propose following:
1) In addition to get_resource_id(), we need **get_all_resource_ids**() : Return all active variables with resource ids
2) **resource_id_update**(existing, new) to move active variables to a specific range,
3) **resource_id_range** (0, PHP_INT_MAX) : This would reset back to start when max is reached.

With these extra methods, long running processes can allocate their active resources to a range and let dynamic resource id allocation out of conflict.

B) Another simpler approach could be: Assuming program creates all permanent resources for that run session after a few seconds, program can call a new method: resource_set_dynamic(). This method should record current+1 resource id in memory as "start point" and whenever overflow is due, it can reset it back to start point. This would avoid conflict with permanent resources which would be already created.

C) Checking against existing IDs could be another approach but this may have some impact on performance.
PHP Version
PHP 8.2.7 (cli) (built: Jul 20 2023 18:02:54) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.2.7, Copyright (c) Zend Technologies
    with Zend OPcache v8.2.7, Copyright (c), by Zend Technologies
Operating System

Debian 12.11

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the long-running daemon case from cache.class.php line 62 using file_put_contents() on /dev/shm with PHP 8.2.7 CLI, then trace the resource-ID allocation reached by that entry point. The issue presents several competing allocation strategies but does not define which behavior or test should establish completion.

Written by the indexing model from the issue text.

Assessment

Tech stack
php
Domain
backend
Issue type
Bug
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.