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From Srinivas Vemula <srinivas.vem...@mensamind.com>
Subject Re: Memory Leaks when web server hangs
Date Mon, 02 Feb 2004 10:56:39 GMT
Oleg,
   
    We are using JDK1.4.1 and connection time out is set to 30Ms and 
read time out to 60Ms. We are trying to connect to a IP Camera, and send 
a heart beat command to the camera to check for its availability every 
30 Secs from the time we find it is un available. If the web server is 
down, we feel that HttpClient is not cleaning up failed connections 
properly and thats resulting in Memory Leaks at the server side.

    The code we use is the standard way of using HttpClient and all the 
code is in a method and new HttpClient object is created for every 
request. Are there any ways to make sure the connections are all being 
purged properly? Are there any precautionary measures or flags we can 
set on HttpClient API when communicating with a web server (running on 
firm ware) with relatively less RAM and processing power (IpCamera with 
built in web server)?

Thanks for your time and help.
Srini

Kalnichevski, Oleg wrote:

>>Mike and Oleg, the stack trace Srini included indicates that HttpClient is
>>attempting to create a new timeout thread on every connection - does this
>>always occur or is it just one timeout thread per httpclient instance?  It
>>would be ideal if we could reduce this to one static thread as starting
>>threads is never nice for server side apps.  Not sure how feasible that is
>>though.
>>    
>>
>
>Hi Srini,
>HttpClient uses an additional controller thread to work around the limitation of older
(< 1.4) JDKs which do not provide a possibility to set connect timeout. If you do not really
need to control connect timeout (for instance, when communicating with an intranet site with
good availability) simply set connect timeout to. That will prevent HttpClient from spawning
an additional thread per request.
>
>Adrian, et al
>Another possibility to use reflection to set connect timeout using the Socket methods
when running in JVM 1.4 or above
>
>Oleg
>
>
>
>-----Original Message-----
>From: Adrian Sutton [mailto:adrian@intencha.com]
>Sent: Monday, February 02, 2004 09:03
>To: Commons HttpClient Project
>Subject: Re: Memory Leaks when web server hangs
>
>
>On 2/2/04 2:00 PM, "Srinivas Vemula" <srinivas.vemula@mensamind.com> wrote:
>
>  
>
>>Hi All,
>>      We are seeing thread leaks when having client open connections to a web
>>server that hangs. Has any one seen this happening?? How do we ensure that the
>>library correctly closes  socket connections on failures, cleaning up system
>>resources, and  threads actually finish in  the timeout period and get freed
>>up. Would using MultiThreadedHttpConnectionManager
>><file:///D:/silkroad/http-commons/commons-httpclient-2.0-rc3/docs/threading.ht
>>ml#MultiThreadedHttpConnectionManager>   be of any help??
>>    
>>
>
>Hi Srini,
>If you're using the same HttpClient instance across multiple threads, you
>must use the MultiThreadedHttpConnectionManager or you'll run into strange
>problems.  If you're using separate HttpClient instances, you may as well
>stick with the single threaded (default) connection manager.
>
>In terms of connections hanging - you probably want to look into the
>setConnectionTimeout and setTimeout methods of the HttpClient class.  These
>allow you to control how long HttpClient waits when making a connection and
>how long it waits for data once the connection is established.  If you have
>set either of these to 0 (not sure what the default is, it may be platform
>specific) the connection will never timeout which sounds a lot like what
>you're seeing.
>
>Mike and Oleg, the stack trace Srini included indicates that HttpClient is
>attempting to create a new timeout thread on every connection - does this
>always occur or is it just one timeout thread per httpclient instance?  It
>would be ideal if we could reduce this to one static thread as starting
>threads is never nice for server side apps.  Not sure how feasible that is
>though.
>
>  
>
>>Srini
>>    
>>
>
>Regards,
>
>Adrian Sutton.
>
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Srinivas Vemula                          +91 40 23547826- Ext 201
Associate Consultant                     +91 40 23541447 (Fax)
Mensamind                                +91 98497-42720 (Mobile)        
Hyderabad
India
http://www.mensamind.com

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