Hi AnuRanjan,
By default the thread dump purge check for older files (default 30 days old per property introscope.enterprisemanager.threaddump.storage.clean.disk.olderthan.days) will occur once per day per property:
introscope.enterprisemanager.threaddump.storage.clean.disk.freq.days=1
So if the logs are only showing the same frequency as that property value then that is expected.
So is Xmx currently set to 4GB in Introscope_Enterprise_Manager.lax?
The top RES value for the process shows higher but that could be explained by other non heap memory usage.
How is the heap usage looking from the Supportability metrics?
If there are no agents connected to the Collector have you tried another Collector restart to see if the same symptoms occur?
If the problem still persists it is probably best to open a Support Case so we can review log and config files in more detail.
Are you using 10.7 GA or a later HF or SP?
Thanks
Lynn