Bug #40557 Error 1037 Out of memory; restart server and try again (needed 2 bytes)
Submitted: 6 Nov 2008 16:29 Modified: 10 Dec 2008 18:30
Reporter: Paul McCullagh (Basic Quality Contributor) (OCA) Email Updates:
Status: No Feedback Impact on me:
Category:MySQL Server Severity:S3 (Non-critical)
Version:5.1 OS:Mac OS X
Assigned to: CPU Architecture:Any
Tags: insufficient file handles, out of memory, qc

[6 Nov 2008 16:29] Paul McCullagh
When too many file handles are used, MySQL returns a miss-leading error:

Error 1037 Out of memory; restart server and try again (needed 2 bytes) 

How to repeat:
It is difficult to reproduce, but should be possible to repeat with the following test:

create table t1 (a int, b int) 
 partition by list(a) subpartition by hash(b) subpartitions 20 
  partition p0 values in (0),
  partition p1 values in (1),
  partition p2 values in (2),
  partition p3 values in (3)
insert into t1 values (1,1),(2,2),(3,3);

Before running the test set the number of file handles very low, e.g:

ulimit -n 20

The error occurs with the following stack trace:

#0  my_open (FileName=0xb00e0d40 "./test/t1.par", Flags=-1341256384, MyFlags=3) at my_open.c:70
#1  0x0015b4c2 in ha_partition::get_from_handler_file (this=0x1730210, name=0x172f4e0 "./test/t1", mem_root=0x172f2dc) at ha_partition.cc:2319
#2  0x0015da8f in ha_partition::initialise_partition (this=0x1730210, mem_root=0x172f2dc) at ha_partition.cc:355
#3  0x0015f6cb in partition_create_handler (hton=0x901c80, share=0x172f2a4, mem_root=0x172f2dc) at ha_partition.cc:110
#4  0x00158a8e in get_new_handler (share=0xb00e0d40, alloc=0xb00e0d40, db_type=0x901c80) at handler.cc:246
#5  0x000e2026 in open_table_def (thd=0x1031000, share=0x172f2a4, db_flags=0) at table.cc:1101

my_open() fails with the error "too many file handles open" if:

    if ((uint) fd >= my_file_limit)

in my_register_filename() which is called from my_open().

[ NOTE: in this case, the fd which is valid is not closed (it is simply discarded), here is the code:

    if ((uint) fd >= my_file_limit)
#if defined(THREAD) && !defined(HAVE_PREAD)
      my_errno= EMFILE;
      DBUG_RETURN(fd);				/* safeguard */

On my mac HAVE_PREAD is not defined so "my_errno= EMFILE" is executed although the file handle is valid! This valid file handle is not closed. ]

After fopen() returns an error, get_from_handler_file() executes the following code:

  else if (get_from_handler_file(table_share->normalized_path.str, mem_root))

In ha_partition.cc line 355. The "Out of memory" appears in the server error log.

So the original reason for the error "too many file handles open" is not reported.
[10 Nov 2008 18:30] Sveta Smirnova
Thank you for the report.

Please indicate accurate version of MySQL server and Mac OS you are running: I get correct error "Out of resources when opening file './test/t1#P#p0#SP#p0sp6.MYD' (Errcode: 24)" on Tiger with current development sources.
[11 Dec 2008 0:00] Bugs System
No feedback was provided for this bug for over a month, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
the status of the bug back to "Open".