Hi Venkat,
You can use Health Mamangement of WAS 8.5.5 configuring custom condition based on PMI counter (DeclaredthreadHungCount) and custom action to send the mail (you need to create your custom script to send the mail)
Or monitor your SystemOut.log to find message like next one and send and email
WSVR0605W: Thread "WebContainer : XX" (XXXXXXX) has been active for YYYYYY milliseconds and may be hung. There is/are 2 thread(s) in total in the server that may be hung.
To take in mind based on Knowledge Center Thread pool counters about Hung Threads has max overhead.
Take a look to next links:
Health management
http://www.ibm.com/support/knowledgecenter/SSAW57_8.5.5/com.ibm.websphere.nd.doc/ae/cwve_odhealth.html
You can also define custom conditions for your health policy if the predefined health conditions do not fit your needs. You define custom conditions as a subexpression that is tested against metrics in your environment. When you define a custom condition, consider the cost of collecting the data, analyzing the data, and if needed, enforcing the health policy. This cost can increase depending on the amount of traffic and number of servers in your network. Analyze the performance of your custom health conditions before you use them in production.
Example:
PMIMetric_FromServerStart$systemModule$cpuUtilization > 90L
You can also define a custom action. With a custom action, you define an executable file to run when the health condition breaches. You must define custom actions before you create the health policy that contains the custom actions.
Health management
https://mediacenter.ibm.com/media/Health+management/0_wau9rldd/33964822
ftp://ftp.software.ibm.com/software/iea/content/com.ibm.iea.was_v8/was/8.5/Architecture/WASV85_Creating_Health_Policies.pdf
Thread pool counters
http://www.ibm.com/support/knowledgecenter/SSAW57_8.5.5/com.ibm.websphere.nd.doc/ae/rprf_datacounter9.html
DeclaredthreadHungCount threadPoolModule.declaredThreadHung The number of threads declared hung Per thread pool CountStatistic All Max 6
https://mediacenter.ibm.com/media/Health+management/0_wau9rldd/33964822
Hope this helps. Tell us if you need more support
Regards