Open Stack

As Pete mentioned, since Swift can use a lot of sockets and fds when the system is under load. Take a look at http://docs.openstack.org/developer/swift/deployment_guide.html#general-system-tuning for some sysctl settings that can help. Also, note that if you start Swift as root (it can drop permissions), it will set the system limits for file descriptors. You may need to use ulimit to increase the number of fds available.

--John





On Jul 11, 2014, at 11:18 AM, Shrinand Javadekar <shrinand at maginatics.com> wrote:

> Thanks for your inputs Edward and Pete. I'll set  sysctl net.ipv4.tcp_tw_reuse.
> 
> On Fri, Jul 11, 2014 at 8:05 AM, Pete Zaitcev <zaitcev at redhat.com> wrote:
>> On Tue, 8 Jul 2014 16:26:10 -0700
>> Shrinand Javadekar <shrinand at maginatics.com> wrote:
>> 
>>> I see that these servers do not use a persistent http connection
>>> between them. So every blob get/put/delete request will create a new
>>> connection, use it and tear it down. In a highly concurrent
>>> environment with thousands of such operations happening per second,
>>> there could be two problems:
>> 
>> It's a well-known problem in Swift. Operators with proxies driving
>> sufficient traffic for it to manifest set sysctl net.ipv4.tcp_tw_reuse.
>> 
>> There were attempts to reuse connections, but they floundered upon
>> the complexities of actually implementing a connection cache.
>> Keep in mind that you still have to allow simultaneous connections
>> to the same node for concurrency. It snowballs quickly.
>> 
>> -- Pete
> 
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