Description of problem:
When I call API method "client.channel.software.listPackagesWithoutChannel(key)",
I get 503 http error. But I have the problem only on server, which was synced some channels and repositories:

I add new channels step by step and test call api - API works fine.

* synced channesl:
rhel-i386-server-5,Red Hat Enterprise Linux (v. 5 for 32-bit x86),12107
rhel-x86_64-server-5,Red Hat Enterprise Linux (v. 5 for 64-bit x86_64),15661
rhel-x86_64-server-6,Red Hat Enterprise Linux Server (v. 6 for 64-bit x86_64),11114
rhel-x86_64-server-vt-5,RHEL Virtualization (v. 5 for 64-bit x86_64),550
rhn-tools-rhel-i386-server-5,Red Hat Network Tools for RHEL Server (v.5 32-bit x86),555
rhn-tools-rhel-x86_64-server-5,Red Hat Network Tools for RHEL Server (v.5 64-bit x86_64),555
rhn-tools-rhel-x86_64-server-6,RHN Tools for RHEL (v. 6 for 64-bit x86_64),120

But When I add repository (rhel 7) and sync it. I got error 503. Same method is in WebUI (for showing packages which aren't in a channel), but webUI works quickly and without problem.

I found only this message in logs.

==> /var/log/tomcat6/catalina.out <==
Nov 5, 2013 8:51:15 AM org.apache.jk.common.ChannelSocket
processConnection WARNING: processCallbacks status 2

Version-Release number of selected component (if applicable):
spacewalk-java-postgresql-2.0.2-46.el6sat.noarch

How reproducible:
sometimes

Steps to Reproduce:
1. sync some big channels
2. create custom big channels and sync it with repository
3. call api: client.channel.software.listPackagesWithoutChannel(key)

Actual results:
Traceback (most recent call last):
  File "/mnt/tests/CoreOS/RHN-Satellite/Helper/manage-channel.py", line 371, in <module>
    delete_free_package(client, key, packageids)
  File "/mnt/tests/CoreOS/RHN-Satellite/Helper/manage-channel.py", line 273, in delete_free_package
    freeids = packages_without_channel(client, key)
  File "/mnt/tests/CoreOS/RHN-Satellite/Helper/manage-channel.py", line 249, in packages_without_channel
    packages = client.channel.software.listPackagesWithoutChannel(key)
  File "/usr/lib64/python2.6/xmlrpclib.py", line 1199, in __call__
    return self.__send(self.__name, args)
  File "/usr/lib64/python2.6/xmlrpclib.py", line 1489, in __request
    verbose=self.__verbose
  File "/usr/lib64/python2.6/xmlrpclib.py", line 1243, in request
    headers
xmlrpclib.ProtocolError: <ProtocolError for dell-per805-01.rhts.eng.bos.redhat.com/rpc/api: 503 Service Temporarily Unavailable>

Expected results:
Result without traceback