Pending queue in the scheduler.
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de Witte
Aug 19, 2011, 12:45:08 PM8/19/11
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Question about the scheduler.
I got several user request a day which include the message :
"This request caused a new process to be started for your application, and thus caused your application code to be loaded for the first time. This request may thus take longer and use more CPU than a typical request for your application."
It seems that this user request triggers the start of a new instance, gets on hold for 2 to 3 seconds, and then being processed by the new instance.
To me it is more logical that the request, triggers a new instance, but in the meantime can be processed by the other instances.
The average latency is 2.0ms, with 2249 requests per instance.
Or do I miss something. I don't want that any user has to wait 2 to.. 8 seconds for a startup.
I got several user request a day which include the message :
"This request caused a new process to be started for your application, and thus caused your application code to be loaded for the first time. This request may thus take longer and use more CPU than a typical request for your application."
It seems that this user request triggers the start of a new instance, gets on hold for 2 to 3 seconds, and then being processed by the new instance.
To me it is more logical that the request, triggers a new instance, but in the meantime can be processed by the other instances.
The average latency is 2.0ms, with 2249 requests per instance.
Or do I miss something. I don't want that any user has to wait 2 to.. 8 seconds for a startup.
Robert Kluin
Aug 21, 2011, 1:49:31 AM8/21/11
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You will probably benefit a lot from a minimum idle instances control. Do you currently have always on enabled?
Robert
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Wendel
Aug 21, 2011, 10:13:19 AM8/21/11
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The website has always at least one instance up because of the regular visitors.
The problem is a design issue in the scheduler, a request that causes a new process to be started, is placed on hold till the new instance becomes available. This can take up to 8 seconds or more, although, based on my logs, this request could easily be handled by another instance, with a delay lesser than 8 seconds. The load on the existing instances will only be temporary higher until the new instance becomes active.
The problem is a design issue in the scheduler, a request that causes a new process to be started, is placed on hold till the new instance becomes available. This can take up to 8 seconds or more, although, based on my logs, this request could easily be handled by another instance, with a delay lesser than 8 seconds. The load on the existing instances will only be temporary higher until the new instance becomes active.
Dale
Aug 22, 2011, 4:36:58 AM8/22/11
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Perhaps you could benefit by enabling warm-up requests?
http://code.google.com/appengine/docs/adminconsole/instances.html#Warmup_Requests
http://code.google.com/appengine/docs/adminconsole/instances.html#Warmup_Requests
de Witte
Aug 22, 2011, 7:23:30 AM8/22/11
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Thanks for the tip. They are already enabled by default, but without effect.
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