Re: Memory Leaks when web server hangs

Eric Bloch Sun, 21 Mar 2004 23:02:50 -0800

I'm happy to change my code but have a version of my product out there that does it this way and wanted to make sure it wasn't in need of immediate patch :-)

-E

Roland Weber wrote:

Hello Eric,
by using the same connection manager for each HttpClient,
you avoid the biggest penalty for creating new clients. But
still, each new client uses up some heap space, which will
have to be garbage collected sooner or later. There are
state objects, and parameter objecs, and probably some
more that will be created. Nothing that hurts much, but what
gain do you expect from creating new HttpClient objects?
You don't have to.
cheers,
 Roland
Eric Bloch <[EMAIL PROTECTED]>
22.03.2004 07:03
Please respond to "Commons HttpClient Project"
To: Commons HttpClient Project <[EMAIL PROTECTED]> cc: Subject: Re: Memory Leaks when web server hangs

Oh... and I just want to know if that's "not the httpclient way", too? That is, should I be reusing the client? What will that get me if I'm already reusing the connection manager?
Thanks again,
Eric
Eric Bloch wrote:
I am creating one MultiThreadedHttpConnectionManager and creating/destroying HttpClient each time but always constructing with the same connection manager. Thanks, Eric

Michael Becke wrote:
Hi Eric,

What exactly do you mean by "thread thrashing"? Which connection manager are you using?

Mike

On Mar 19, 2004, at 1:21 PM, Eric Bloch wrote:
Hey there,

I create/destroy http clients but always have them use the same connection manager.

Will that cause thread thrashing?

Thanks,

-Eric

Roland Weber wrote:
Hello Srini,
you should *not* create a new HTTP Client for each request!
This will also create a new connection manager, and a new
cleanup thread. It beats the whole purpose of connection
management.
You should create *one* HTTP Client object for the lifetime
of your application. Then, the connection manager of that
client will reuse and free connections as appropriate.
best regards,
Roland
Srinivas Vemula <[EMAIL PROTECTED]> 02.02.2004 11:56 Please respond to "Commons HttpClient Project" To: Commons HttpClient Project <[EMAIL PROTECTED]> cc: Subject: Re: Memory Leaks when web server hangs

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:[EMAIL PROTECTED]
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" <[EMAIL PROTECTED]>
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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Re: Memory Leaks when web server hangs

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