Out of Memory Error in android due to Heap Size Increasing

I am having out of Memory error. I am working on live chat application. It is working fine but when I run the app 1 to 2 hours continuously the heap size is increasing and when I do chatting then again close chat generate chat it is being crashed. In my app I am using web services.

When the heap size is increasing and reach to 16 MB application begin to hang and after some time being crashed. Showing out of memory due to heap size because the resultant heap size is greater than allocated.

I am testing my application on HTC Explorer. In my application most of the activities are using background thread and for that i am using Asnyc Task.

I am getting error like the following.

04-30 16:53:14.658: E/AndroidRuntime(5707): FATAL EXCEPTION: MagentoBackground
 04-30 16:53:14.658: E/AndroidRuntime(5707): java.lang.OutOfMemoryError: (Heap Size=20167KB, Allocated=16063KB, Bitmap Size=355KB)
 04-30 16:53:14.658: E/AndroidRuntime(5707):     at org.apache.http.util.ByteArrayBuffer.<init>(ByteArrayBuffer.java:53)
 04-30 16:53:14.658: E/AndroidRuntime(5707):     at org.apache.http.impl.io.AbstractSessionInputBuffer.init(AbstractSessionInputBuffer.java:82)
 04-30 16:53:14.658: E/AndroidRuntime(5707):     at org.apache.http.impl.io.SocketInputBuffer.<init>(SocketInputBuffer.java:98)
 04-30 16:53:14.658: E/AndroidRuntime(5707):     at org.apache.http.impl.SocketHttpClientConnection.createSessionInputBuffer(SocketHttpClientConnection.java:83)
 04-30 16:53:14.658: E/AndroidRuntime(5707):     at org.apache.http.impl.conn.DefaultClientConnection.createSessionInputBuffer(DefaultClientConnection.java:170)
 04-30 16:53:14.658: E/AndroidRuntime(5707):     at org.apache.http.impl.SocketHttpClientConnection.bind(SocketHttpClientConnection.java:106)
 04-30 16:53:14.658: E/AndroidRuntime(5707):     at org.apache.http.impl.conn.DefaultClientConnection.openCompleted(DefaultClientConnection.java:129)
 04-30 16:53:14.658: E/AndroidRuntime(5707):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:173)
 04-30 16:53:14.658: E/AndroidRuntime(5707):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
 04-30 16:53:14.658: E/AndroidRuntime(5707):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
 04-30 16:53:14.658: E/AndroidRuntime(5707):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:359)
 04-30 16:53:14.658: E/AndroidRuntime(5707):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
 04-30 16:53:14.658: E/AndroidRuntime(5707):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
 04-30 16:53:14.658: E/AndroidRuntime(5707):     at com.live2support.CustomHttpClient.executeHttpPost1(CustomHttpClient.java:163)
 

Is there limit of heap size?

how can i solve my issue?

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