mysql unable to open more that a 1020 connections

[Harper Mann]

Try setting

net.ipv4.tcp_max_syn_backlog = 1024

to 

sysctl -w net.ipv4.tcp_max_syn_backlog = 2048

Hope this helps,

- Harper

Harper Mann
Groundwork Open Source Solutions
510-599-2075 (cell)
http://itgroundwork.com


> -----Original Message-----
> From: redhat-list-bounces at redhat.com [mailto:redhat-list-
> bounces at redhat.com] On Behalf Of Aaron Walker
> Sent: Friday, February 11, 2005 8:52 AM
> To: redhat-list at redhat.com
> Subject: mysql unable to open more that a 1020 connections
> 
> Hello,
> I am having trouble getting a mysql server to open more than 1020
> connections.
> 
> Background:
> I am in the process of upgrading from redhat 9 to rhel 3.  The old
> server could quite
> happily open up  1500 connections, but the new  rhel 3 always stops at
> 1020 connections.
> Both the rh9 and rhel 3 are using the same mysql versions and
> configurations.
> 
> Hardware  and kernel version
> The rhel 3 system
>      kernel  2.4.21-27.ELsmp
>     quad opteron 32 GB RAM.
> The rh 9
>     Kernel 2.4.20-8bigmem
>     dual xeon 12 GB RAM
> 
> Both kernel are standard ones that are shipped with RedHat.
> 
> Things I have changed
>  /proc/sys/fs/file-max and I am no where near the limit set there.
> I have also looked at the output of sysctl -a but I cant see any obvoius
> things I could change.
> The output of which is included at the bottom
>  I have also looked at changing the values retruned by ulimit -a
> in particular the open files it was set to 1020 and is now set to 3000.
> 
> Any help here would be much appreciated.
> 
> Thanks
> 
> Aaron
> 
> 
> vm.skip_mapped_pages = 0
> vm.stack_defer_threshold = 2048
> vm.inactive_clean_percent = 30
> vm.dcache_priority = 0
> vm.hugetlb_pool = 0
> vm.max_map_count = 65536
> vm.max-readahead = 31
> vm.min-readahead = 3
> vm.page-cluster = 3
> vm.pagetable_cache = 25 50
> vm.kswapd = 512 32      8
> vm.pagecache = 1        15      30
> vm.overcommit_ratio = 50
> vm.overcommit_memory = 0
> vm.bdflush = 50 500     0       0       500     3000    80      50      0
> kernel.mem_nmi_panic = 0
> kernel.unknown_nmi_panic = 0
> kernel.sercons_esc = -1
> kernel.overflowgid = 65534
> kernel.overflowuid = 65534
> kernel.random.uuid = 8808693b-9dc4-418e-9519-8d751a7ff333
> kernel.random.boot_id = 173aabe6-fc44-4042-bae3-e8652c0db634
> kernel.random.write_wakeup_threshold = 128
> kernel.random.read_wakeup_threshold = 64
> kernel.random.entropy_avail = 2480
> kernel.random.poolsize = 512
> kernel.pid_max = 32768
> kernel.threads-max = 14336
> kernel.cad_pid = 1
> kernel.sysrq-timer = 10
> kernel.sysrq-sticky = 0
> kernel.sysrq-key = 84
> kernel.sysrq = 0
> kernel.sem = 250        32000   32      128
> kernel.msgmnb = 16384
> kernel.msgmni = 16
> kernel.msgmax = 8192
> kernel.shmmni = 4096
> kernel.shmall = 2097152
> kernel.shmmax = 33554432
> kernel.rtsig-max = 1024
> kernel.rtsig-nr = 0
> kernel.acct = 4 2       30
> kernel.hotplug = /sbin/hotplug
> kernel.modprobe = /sbin/modprobe
> kernel.printk = 6       4       1       7
> kernel.ctrl-alt-del = 0
> kernel.real-root-dev = 256
> kernel.task_size = -1073741824
> kernel.cap-bound = -257
> kernel.tainted = 0
> kernel.core_pattern = core
> kernel.core_setuid_ok = 0
> kernel.core_uses_pid = 1
> kernel.use-nx = 0
> kernel.exec-shield-randomize = 1
> kernel.exec-shield = 1
> kernel.print_fatal_signals = 0
> kernel.panic_on_oops = 1
> kernel.panic = 0
> kernel.domainname = (none)
> kernel.hostname = db4.ixe.activehotels.com
> kernel.version = #1 SMP Wed Dec 1 21:59:02 EST 2004
> kernel.osrelease = 2.4.21-27.ELsmp
> kernel.ostype = Linux
> fs.quota.syncs = 21
> fs.quota.free_dquots = 0
> fs.quota.allocated_dquots = 0
> fs.quota.cache_hits = 0
> fs.quota.writes = 0
> fs.quota.reads = 0
> fs.quota.drops = 0
> fs.quota.lookups = 0
> fs.aio-pinned = 0
> fs.aio-max-pinned = 2097152
> fs.aio-max-size = 131072
> fs.aio-max-nr = 65536
> fs.aio-nr = 0
> fs.lease-break-time = 45
> fs.dir-notify-enable = 1
> fs.leases-enable = 1
> fs.overflowgid = 65534
> fs.overflowuid = 65534
> fs.dentry-state = 2323  1381    45      0       0       0
> fs.file-max = 3355443
> fs.file-nr = 3874       393     3355443
> fs.inode-state = 8701   6688    0       0       0       0       0
> fs.inode-nr = 8701      6688
> 
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