Fix deadlock on sending data concurrently to pattern query

[Allan-QLB]

Purpose

Resolves issue#1790

Goals

make SingleProcessStreamReceiver always synchronize patternSyncObject before locking the lockWrapper in process method

Approach

1 Modify ProcessStreamReceiver#process to be protected method 2 Overwrite the process mothod in SingleProcessStreamReceiver, in the method we synchronize the patternSyncObject first then call the process method of super class 3 delete synchronization of patternSyncObject in the processAndClear method

Release note

Fix deadlock on sending data concurrently to pattern query

Documentation

N/A

Automation tests

N/A

Security checks

• Followed secure coding standards in http://wso2.com/technical-reports/wso2-secure-engineering-guidelines? yes
• Ran FindSecurityBugs plugin and verified report? yes
• Confirmed that this PR doesn't commit any keys, passwords, tokens, usernames, or other secrets? yes

Samples

Related PRs

Test environment

1.8

[CLAassistant]

All committers have signed the CLA.