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On 03/01/2012 02:45 PM, Yun Mao wrote:
> There are plenty eventlet discussion recently but I'll stick my
> question to this thread, although it's pretty much a separate
> question. :)
>
> How is MySQL access handled in eventlet? Presumably it's external C
> library so it's not going to be monkey patched. Does that make every
> db access call a blocking call? Thanks,

Nope, it goes through a thread pool.
>
> Yun
>
> On Wed, Feb 29, 2012 at 9:18 PM, Johannes Erdfelt<johannes at erdfelt.com>  wrote:
>> On Wed, Feb 29, 2012, Yun Mao<yunmao at gmail.com>  wrote:
>>> Thanks for the explanation. Let me see if I understand this.
>>>
>>> 1. Eventlet will never have this problem if there is only 1 OS thread
>>> -- let's call it main thread.
>> In fact, that's exactly what Python calls it :)
>>
>>> 2. In Nova, there is only 1 OS thread unless you use xenapi and/or the
>>> virt/firewall driver.
>>> 3. The python logging module uses locks. Because of the monkey patch,
>>> those locks are actually eventlet or "green" locks and may trigger a
>>> green thread context switch.
>>>
>>> Based on 1-3, does it make sense to say that in the other OS threads
>>> (i.e. not main thread), if logging (plus other pure python library
>>> code involving locking) is never used, and we do not run a eventlet
>>> hub at all, we should never see this problem?
>> That should be correct. I'd have to double check all of the monkey
>> patching that eventlet does to make sure there aren't other cases where
>> you may inadvertently use eventlet primitives across real threads.
>>
>> JE
>>
>>
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