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Bug 1519134

Summary:	Deadlock while changing system's child channels subscription and manipulating the child channel in the same time
Product:	Red Hat Satellite 5	Reporter:	Radovan Drazny <rdrazny>
Component:	Server	Assignee:	Tomáš Kašpárek <tkasparek>
Status:	CLOSED DEFERRED	QA Contact:	Red Hat Satellite QA List <satqe-list>
Severity:	low	Docs Contact:
Priority:	unspecified
Version:	580	CC:	tlestach
Target Milestone:	---
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-04-10 08:47:16 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	1482563

Description Radovan Drazny 2017-11-30 08:59:12 UTC

Description of problem:
Encountered while testing the fix for BZ 1452362. This deadlock is triggered only during an extremely rare user scenario (we are subscribing to a channel, while we actually delete the channel), so it's not a critical problem. Still, it can be symptom of a problem in some more probable user scenario, so let's have it documented.

Version-Release number of selected component (if applicable):
spacewalk-backend-2.5.3-157.el6sat.noarch
spacewalk-schema-2.5.1-53.el6sat.noarch
satellite-schema-5.8.0.37-1.el6sat.noarch

How reproducible:
always

Steps to Reproduce:
1. Have a lot of systems registered to a Sat 5.8 server (1200 fake regs in my case)
2. All these systems are subscribed to rhel-x86_64-server-6 base channel and rhn-tools-rhel-x86_64-server-6 child channel
3. Have four clients running the ./setbase_label.pl 4 X reproducer script from BZ 1452362
4. Run "spacewalk-remove-channel -c rhn-tools-rhel-x86_64-server-6 --unsubscribe" on the sat server

Actual results:

Result in the server shell:

$ spacewalk-remove-channel -c rhn-tools-rhel-x86_64-server-6 --unsubscribe

The following channels will have their systems unsubscribed:
rhn-tools-rhel-x86_64-server-6           1110
                  ________________________________________
Unsubscribing:
ERROR: unhandled exception occurred: ((99999, 'ERROR:  deadlock detected', 
'DETAIL:  Process 18222 waits for ShareLock on transaction 190922; blocked by 
process 18208.\nProcess 18208 waits for AccessExclusiveLock on tuple (6,26) of 
relation 20451 of database 16384; blocked by process 18187.\nProcess 18187 
waits for ShareLock on transaction 190919; blocked by process 18222.\nHINT:  
See server log for query details.\nCONTEXT:  while locking tuple (0,11) in 
relation "rhnserver"\nSQL statement "select s.created                     from 
rhnServer s\n     where s.id = server_id_in\n       for update"\nPL/pgSQL 
function lock_counts(numeric) line 6 at SQL statement\nSQL statement "SELECT 
lock_counts(server_id_in)"\nPL/pgSQL function 
rhn_channel.unsubscribe_server(numeric,numeric,numeric,numeric,numeric,numeric) 
line 19 at PERFORM\n', TransactionRollbackError('deadlock detected\nDETAIL:  
Process 18222 waits for ShareLock on transaction 190922; blocked by process 
18208.\nProcess 18208 waits for AccessExclusiveLock on tuple (6,26) of 
relation 20451 of database 16384; blocked by process 18187.\nProcess 18187 
waits for ShareLock on transaction 190919; blocked by process 18222.\nHINT:  
See server log for query details.\nCONTEXT:  while locking tuple (0,11) in 
relation "rhnserver"\nSQL statement "select s.created                     from 
rhnServer s\n     where s.id = server_id_in\n       for update"\nPL/pgSQL 
function lock_counts(numeric) line 6 at SQL statement\nSQL statement "SELECT 
lock_counts(server_id_in)"\nPL/pgSQL function 
rhn_channel.unsubscribe_server(numeric,numeric,numeric,numeric,numeric,numeric) 
line 19 at PERFORM\n',))).
Traceback (most recent call last):
  File "/usr/bin/spacewalk-remove-channel", line 182, in <module>
    sys.exit(main() or 0)
  File "/usr/bin/spacewalk-remove-channel", line 154, in main
    if __serverCheck(channels.keys(), options.unsubscribe):
  File "/usr/lib/python2.6/site-packages/spacewalk/satellite_tools/
contentRemove.py", line 41, in __serverCheck
    return __unsubscribeServers(labels)
  File "/usr/lib/python2.6/site-packages/spacewalk/satellite_tools/
contentRemove.py", line 91, in __unsubscribeServers
    unsubscribe_server_proc(i['server_id'], i['channel_id'])
  File "/usr/lib/python2.6/site-packages/spacewalk/server/rhnSQL/
driver_postgresql.py", line 116, in __call__
    result = Function.__call__(self, *args)
  File "/usr/lib/python2.6/site-packages/spacewalk/server/rhnSQL/
driver_postgresql.py", line 92, in __call__
    raise sql_base.SQLSchemaError(error_code, e.pgerror, e)
SQLSchemaError: (99999, 'ERROR:  deadlock detected', 'DETAIL:  Process 18222 
waits for ShareLock on transaction 190922; blocked by process 18208.\nProcess 
18208 waits for AccessExclusiveLock on tuple (6,26) of relation 20451 of 
database 16384; blocked by process 18187.\nProcess 18187 waits for ShareLock 
on transaction 190919; blocked by process 18222.\nHINT:  See server log for 
query details.\nCONTEXT:  while locking tuple (0,11) in relation 
"rhnserver"\nSQL statement "select s.created                     from 
rhnServer s\n     where s.id = server_id_in\n       for update"\nPL/pgSQL 
function lock_counts(numeric) line 6 at SQL statement\nSQL statement "SELECT 
lock_counts(server_id_in)"\nPL/pgSQL function 
rhn_channel.unsubscribe_server(numeric,numeric,numeric,numeric,numeric,numeric) 
line 19 at PERFORM\n', TransactionRollbackError('deadlock detected\nDETAIL:  
Process 18222 waits for ShareLock on transaction 190922; blocked by process 
18208.\nProcess 18208 waits for AccessExclusiveLock on tuple (6,26) of 
relation 20451 of database 16384; blocked by process 18187.\nProcess 18187 
waits for ShareLock on transaction 190919; blocked by process 18222.\nHINT:  
See server log for query details.\nCONTEXT:  while locking tuple (0,11) in 
relation "rhnserver"\nSQL statement "select s.created                     from 
rhnServer s\n     where s.id = server_id_in\n       for update"\nPL/pgSQL 
function lock_counts(numeric) line 6 at SQL statement\nSQL statement "SELECT 
lock_counts(server_id_in)"\nPL/pgSQL function 
rhn_channel.unsubscribe_server(numeric,numeric,numeric,numeric,numeric,numeric) 
line 19 at PERFORM\n',))

===================================================
===================================================

Error in the /var/log/tomcat6/catalina.out:

2017-11-29 12:38:48,079 [TP-Processor8] ERROR 
com.redhat.rhn.frontend.xmlrpc.BaseHandler - Error calling method: 
java.lang.reflect.InvocationTargetException
        at sun.reflect.GeneratedMethodAccessor522.invoke(Unknown Source)
        at 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:
55)
        at java.lang.reflect.Method.invoke(Method.java:508)
        at com.redhat.rhn.frontend.xmlrpc.BaseHandler.invoke(BaseHandler.java:
174)
        at redstone.xmlrpc.XmlRpcDispatcher.dispatch(XmlRpcDispatcher.java:
123)
        at 
com.redhat.rhn.frontend.xmlrpc.RhnXmlRpcServer.execute(RhnXmlRpcServer.java:
54)
        at 
com.redhat.rhn.frontend.xmlrpc.XmlRpcServlet.doPost(XmlRpcServlet.java:162)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:643)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
        at 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:
290)
        at 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:
206)
        at 
com.opensymphony.sitemesh.webapp.SiteMeshFilter.obtainContent(SiteMeshFilter.java:
129)
        at 
com.opensymphony.sitemesh.webapp.SiteMeshFilter.doFilter(SiteMeshFilter.java:
77)
        at 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:
235)
        at 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:
206)
        at 
com.redhat.rhn.frontend.servlets.LocalizedEnvironmentFilter.doFilter(LocalizedEnvironmentFilter.java:
67)
        at 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:
235)
        at 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:
206)
        at 
com.redhat.rhn.frontend.servlets.EnvironmentFilter.doFilter(EnvironmentFilter.java:
101)
        at 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:
235)
        at 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:
206)
        at 
com.redhat.rhn.frontend.servlets.SessionFilter.doFilter(SessionFilter.java:57)
        at 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:
235)
        at 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:
206)
        at 
com.redhat.rhn.frontend.servlets.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:
97)
        at 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:
235)
        at 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:
206)
        at 
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:
233)
        at 
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:
191)
        at 
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at 
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
        at 
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:
109)
        at 
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:299)
        at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:
190)
        at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:291)
        at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:769)
        at 
org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:698)
        at org.apache.jk.common.ChannelSocket
$SocketConnection.runIt(ChannelSocket.java:891)
        at org.apache.tomcat.util.threads.ThreadPool
$ControlRunnable.run(ThreadPool.java:690)
        at java.lang.Thread.run(Thread.java:785)
Caused by: 
com.redhat.rhn.common.db.WrappedSQLException: ERROR: deadlock detected
  Detail: Process 18218 waits for ShareLock on transaction 190919; blocked by 
process 18222.
Process 18222 waits for ShareLock on transaction 190922; blocked by process 
18208.
Process 18208 waits for AccessExclusiveLock on tuple (6,26) of relation 20451 
of database 16384; blocked by process 18218.
  Hint: See server log for query details.
  Where: while locking tuple (6,26) in relation "rhnprivatechannelfamily"
SQL statement "select pcf.created                     from 
rhnPrivateChannelFamily pcf
           inner join rhnserver s on s.org_id = pcf.org_id
     where s.id = server_id_in
     order by channel_family_id asc
       for update"
PL/pgSQL function lock_counts(numeric) line 11 at SQL statement
SQL statement "SELECT lock_counts(server_id_in)"
PL/pgSQL function 
rhn_channel.unsubscribe_server(numeric,numeric,numeric,numeric,numeric,numeric) 
line 19 at PERFORM
        at 
com.redhat.rhn.common.translation.SqlExceptionTranslator.postgreSqlException(SqlExceptionTranslator.java:
54)
        at 
com.redhat.rhn.common.translation.SqlExceptionTranslator.sqlException(SqlExceptionTranslator.java:
44)
        at 
com.redhat.rhn.common.db.datasource.CachedStatement.executeCallable(CachedStatement.java:
487)
        at 
com.redhat.rhn.common.db.datasource.CallableMode.execute(CallableMode.java:39)
        at 
com.redhat.rhn.manager.system.SystemManager.unsubscribeServerFromChannel(SystemManager.java:
1557)
        at 
com.redhat.rhn.manager.system.SystemManager.unsubscribeServerFromChannel(SystemManager.java:
1531)
        at 
com.redhat.rhn.manager.system.SystemManager.unsubscribeServerFromChannel(SystemManager.java:
1488)
        at 
com.redhat.rhn.manager.system.SystemManager.unsubscribeServerFromChannel(SystemManager.java:
1449)
        at 
com.redhat.rhn.manager.system.UpdateChildChannelsCommand.unsubscribeFromOldChannels(UpdateChildChannelsCommand.java:
194)
        at 
com.redhat.rhn.manager.system.UpdateChildChannelsCommand.store(UpdateChildChannelsCommand.java:
107)
        at 
com.redhat.rhn.manager.system.UpdateBaseChannelCommand.store(UpdateBaseChannelCommand.java:
101)
        at 
com.redhat.rhn.frontend.xmlrpc.system.SystemHandler.setBaseChannel(SystemHandler.java:
472)
        ... 40 more
Caused by: 
org.postgresql.util.PSQLException: ERROR: deadlock detected
  Detail: Process 18218 waits for ShareLock on transaction 190919; blocked by 
process 18222.
Process 18222 waits for ShareLock on transaction 190922; blocked by process 
18208.
Process 18208 waits for AccessExclusiveLock on tuple (6,26) of relation 20451 
of database 16384; blocked by process 18218.
  Hint: See server log for query details.
  Where: while locking tuple (6,26) in relation "rhnprivatechannelfamily"
SQL statement "select pcf.created                     from 
rhnPrivateChannelFamily pcf
           inner join rhnserver s on s.org_id = pcf.org_id
     where s.id = server_id_in
     order by channel_family_id asc
       for update"
PL/pgSQL function lock_counts(numeric) line 11 at SQL statement
SQL statement "SELECT lock_counts(server_id_in)"
PL/pgSQL function 
rhn_channel.unsubscribe_server(numeric,numeric,numeric,numeric,numeric,numeric) 
line 19 at PERFORM
        at 
org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:
2094)
        at 
org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:
1827)
        at 
org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:255)
        at 
org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:
508)
        at 
org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:
384)
        at 
org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:
377)
        at 
com.mchange.v2.c3p0.impl.NewProxyCallableStatement.execute(NewProxyCallableStatement.java:
2706)
        at 
com.redhat.rhn.common.db.NamedPreparedStatement.execute(NamedPreparedStatement.java:
117)
        at 
com.redhat.rhn.common.db.datasource.CachedStatement.executeCallable(CachedStatement.java:
474)
        ... 49 more
2017-11-29 12:38:48,083 [TP-Processor8] ERROR 
com.redhat.rhn.frontend.xmlrpc.BaseHandler - Caused by: 
com.redhat.rhn.common.db.WrappedSQLException: ERROR: deadlock detected
  Detail: Process 18218 waits for ShareLock on transaction 190919; blocked by 
process 18222.
Process 18222 waits for ShareLock on transaction 190922; blocked by process 
18208.
Process 18208 waits for AccessExclusiveLock on tuple (6,26) of relation 20451 
of database 16384; blocked by process 18218.
  Hint: See server log for query details.
  Where: while locking tuple (6,26) in relation "rhnprivatechannelfamily"
SQL statement "select pcf.created                     from 
rhnPrivateChannelFamily pcf
           inner join rhnserver s on s.org_id = pcf.org_id
     where s.id = server_id_in
     order by channel_family_id asc
       for update"
PL/pgSQL function lock_counts(numeric) line 11 at SQL statement
SQL statement "SELECT lock_counts(server_id_in)"
PL/pgSQL function 
rhn_channel.unsubscribe_server(numeric,numeric,numeric,numeric,numeric,numeric) 
line 19 at PERFORM
        at 
com.redhat.rhn.common.translation.SqlExceptionTranslator.postgreSqlException(SqlExceptionTranslator.java:
54)
        at 
com.redhat.rhn.common.translation.SqlExceptionTranslator.sqlException(SqlExceptionTranslator.java:
44)
        at 
com.redhat.rhn.common.db.datasource.CachedStatement.executeCallable(CachedStatement.java:
487)
        at 
com.redhat.rhn.common.db.datasource.CallableMode.execute(CallableMode.java:39)
        at 
com.redhat.rhn.manager.system.SystemManager.unsubscribeServerFromChannel(SystemManager.java:
1557)
        at 
com.redhat.rhn.manager.system.SystemManager.unsubscribeServerFromChannel(SystemManager.java:
1531)
        at 
com.redhat.rhn.manager.system.SystemManager.unsubscribeServerFromChannel(SystemManager.java:
1488)
        at 
com.redhat.rhn.manager.system.SystemManager.unsubscribeServerFromChannel(SystemManager.java:
1449)
        at 
com.redhat.rhn.manager.system.UpdateChildChannelsCommand.unsubscribeFromOldChannels(UpdateChildChannelsCommand.java:
194)
        at 
com.redhat.rhn.manager.system.UpdateChildChannelsCommand.store(UpdateChildChannelsCommand.java:
107)
        at 
com.redhat.rhn.manager.system.UpdateBaseChannelCommand.store(UpdateBaseChannelCommand.java:
101)
        at 
com.redhat.rhn.frontend.xmlrpc.system.SystemHandler.setBaseChannel(SystemHandler.java:
472)
        at sun.reflect.GeneratedMethodAccessor522.invoke(Unknown Source)
        at 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:
55)
        at java.lang.reflect.Method.invoke(Method.java:508)
        at com.redhat.rhn.frontend.xmlrpc.BaseHandler.invoke(BaseHandler.java:
174)
        at redstone.xmlrpc.XmlRpcDispatcher.dispatch(XmlRpcDispatcher.java:
123)
        at 
com.redhat.rhn.frontend.xmlrpc.RhnXmlRpcServer.execute(RhnXmlRpcServer.java:
54)
        at 
com.redhat.rhn.frontend.xmlrpc.XmlRpcServlet.doPost(XmlRpcServlet.java:162)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:643)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
        at 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:
290)
        at 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:
206)
        at 
com.opensymphony.sitemesh.webapp.SiteMeshFilter.obtainContent(SiteMeshFilter.java:
129)
        at 
com.opensymphony.sitemesh.webapp.SiteMeshFilter.doFilter(SiteMeshFilter.java:
77)
        at 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:
235)
        at 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:
206)
        at 
com.redhat.rhn.frontend.servlets.LocalizedEnvironmentFilter.doFilter(LocalizedEnvironmentFilter.java:
67)
        at 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:
235)
        at 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:
206)
        at 
com.redhat.rhn.frontend.servlets.EnvironmentFilter.doFilter(EnvironmentFilter.java:
101)
        at 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:
235)
        at 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:
206)
        at 
com.redhat.rhn.frontend.servlets.SessionFilter.doFilter(SessionFilter.java:57)
        at 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:
235)
        at 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:
206)
        at 
com.redhat.rhn.frontend.servlets.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:
97)
        at 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:
235)
        at 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:
206)
        at 
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:
233)
        at 
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:
191)
        at 
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at 
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
        at 
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:
109)
        at 
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:299)
        at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:
190)
        at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:291)
        at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:769)
        at 
org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:698)
        at org.apache.jk.common.ChannelSocket
$SocketConnection.runIt(ChannelSocket.java:891)
        at org.apache.tomcat.util.threads.ThreadPool
$ControlRunnable.run(ThreadPool.java:690)
        at java.lang.Thread.run(Thread.java:785)
Caused by: 
org.postgresql.util.PSQLException: ERROR: deadlock detected
  Detail: Process 18218 waits for ShareLock on transaction 190919; blocked by 
process 18222.
Process 18222 waits for ShareLock on transaction 190922; blocked by process 
18208.
Process 18208 waits for AccessExclusiveLock on tuple (6,26) of relation 20451 
of database 16384; blocked by process 18218.
  Hint: See server log for query details.
 Where: while locking tuple (6,26) in relation "rhnprivatechannelfamily"
SQL statement "select pcf.created                     from 
rhnPrivateChannelFamily pcf
           inner join rhnserver s on s.org_id = pcf.org_id
     where s.id = server_id_in
     order by channel_family_id asc
       for update"
PL/pgSQL function lock_counts(numeric) line 11 at SQL statement
SQL statement "SELECT lock_counts(server_id_in)"
PL/pgSQL function 
rhn_channel.unsubscribe_server(numeric,numeric,numeric,numeric,numeric,numeric) 
line 19 at PERFORM
        at 
org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:
2094)
        at 
org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:
1827)
        at 
org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:255)
        at 
org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:
508)
        at 
org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:
384)
        at 
org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:
377)
        at 
com.mchange.v2.c3p0.impl.NewProxyCallableStatement.execute(NewProxyCallableStatement.java:
2706)
        at 
com.redhat.rhn.common.db.NamedPreparedStatement.execute(NamedPreparedStatement.java:
117)
        at 
com.redhat.rhn.common.db.datasource.CachedStatement.executeCallable(CachedStatement.java:
474)
        ... 49 more
2017-11-29 12:38:48,084 [TP-Processor8] ERROR 
com.redhat.rhn.frontend.xmlrpc.BaseHandler - Rolling back transaction
Nov 29, 2017 12:38:48 PM redstone.xmlrpc.XmlRpcDispatcher writeError
WARNING: redstone.xmlrpc.XmlRpcFault: unhandled internal exception: ERROR: 
deadlock detected
  Detail: Process 18218 waits for ShareLock on transaction 190919; blocked by 
process 18222.
Process 18222 waits for ShareLock on transaction 190922; blocked by process 
18208.
Process 18208 waits for AccessExclusiveLock on tuple (6,26) of relation 20451 
of database 16384; blocked by process 18218.
  Hint: See server log for query details.
  Where: while locking tuple (6,26) in relation "rhnprivatechannelfamily"
SQL statement "select pcf.created                     from 
rhnPrivateChannelFamily pcf
           inner join rhnserver s on s.org_id = pcf.org_id
     where s.id = server_id_in
     order by channel_family_id asc
       for update"
PL/pgSQL function lock_counts(numeric) line 11 at SQL statement
SQL statement "SELECT lock_counts(server_id_in)"
PL/pgSQL function 
rhn_channel.unsubscribe_server(numeric,numeric,numeric,numeric,numeric,numeric) 
line 19 at PERFORM

Expected results:
Server should handle this "conflict of interests" more gracefully. 

Additional info:

Comment 1 Tomas Lestach 2018-04-10 08:47:16 UTC

We have re-reviewed this bug, as part of an ongoing effort to improve Satellite/Proxy feature and bug updates, review and backlog.

This bug has currently no open customer cases. While this bug may still valid, we do not see it being implemented prior to the EOL of the Satellite 5.x product. As such, this is being CLOSED DEFERRED.