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SAP Basis/Netweaver Tutorials, Monitoring, Administration(Certification) and FAQs


Thursday, 24 May 2012

How to restart java stack from abap stack in sap?



This article answers following queries :



ü  Can we restart java stack from abap stack in sap?
ü  How to restart java stack from abap stack in sap?
ü  What is the transaction code used to restart java stack in sap?
ü  How to restart the java stack of an sap netweaver add in installation?
ü  How to restart java stack in an ABAP + Java stack system?
ü  How to restart all java instances of an SAP system from ABAP stack?
ü  How to bring down java stack of an application server from abap level?
ü  How to bring down entire java cluster of an SAP system from ABAP stack?
ü  What is the difference between soft shutdown and hard shut down of java stack in SMICM?
ü  What are the different ways of restarting java stack of an SAP system?

ü  Which java shutdown / restart method should be used in cases of emergency in SAP?


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Yes. Java stack can be restarted from abap stack in sap.
SMICM is the transaction code used to restart the java stack in an ABAP + Java stack system.
Login to abap stack of an SAP system and  choose transaction SMICM and navigate to  
Administration -> AS Java -> Instance (Local) -> Send soft shutdown -> with restart
Please find below screenshot :
























Please note, if restart is not required and if you want to only bring down the java stack then choose without restart option in the above SMICM screen.
Administration -> AS Java -> Instance (Local) -> Send soft shutdown -> without restart

Please note in the above method, we can only restart or bring down local java stack of an instance. If you would like to restart entire java cluster of an sap system (ie. Global), in SMICM transaction, navigate to
Administration -> AS Java -> Cluster (Global) -> Send soft shutdown -> with restart


Please find  below screenshot for the same



























If you would like to just bring down entire java cluster of an SAP system, then navigate as below in SMICM transaction
Administration -> AS Java -> Cluster (Global) -> Send soft shutdown -> without restart

Also there are 2 methods in restart or bringing down the java stack.
 They are
1)Send Soft shutdown : In this method, the abap dispatcher sends a SIGQUIT message to the jstart process. The AS java will be terminated with a soft shutdown.  It means, the abap dispatcher will not actively close the connection. It will wait and  finish the processing of all the running requests and then shuts down.

2)Send Hard shutdown : In this method, the abap dispatcher sends a SIGINT message to the jstart process. The AS java will be terminated with a hard shutdown. It means, java processes will get some time to close. If that time is not sufficient, they are closed with a hard shut down.

The main difference between soft shut down and hard shut down is the hard shut down will happen quickly  within  few minutes where as the soft shut down will happen only after completing the processing of all running requests.

Ending the process (with or without a restart) :

We can also bring down or restart java by using the option “End process” in SMICM.
The abap dispatcher sets the restart flag for AS java and sends the SIGKILL signal to the jstart process. This terminates the jstart and the AS java with a hard shut down.

Please note that this option should be used only in emergency as processes shutdown in this way will no longer be able to reach stable state.

Please navigate as below to do the same for local instance.
      Administration -> AS Java -> Instance (Local) -> End process  -> without restart
     Or
      Administration -> AS Java -> Instance (Local) -> End process  -> with restart
























Please navigate as below to bring down or restart java globally for all java clusters.
      Administration -> AS Java -> Cluster (Global) -> End Process  -> without restart
Or
      Administration -> AS Java -> Cluster (Global) -> End Process  -> with restart