Macbook Pro heats up and shuts down after the updates to 10.9.x

At times I think why?
Why did I decide to upgrade the OS. It was cool with 10.8.x. I even had upgraded the RAM: from 4 GB to 8GB, thereby leaving plenty of 'em for spare RAM (without needing to download more RAM.. wink wink).
One evening I saw that there were more than 5 GB of RAM consistently being not used. So, I thought may be going for 10.9 will be OK. Bad decision. I think Mars eclipse was happening at the time when I made that decision.

Fast forward now:
Now and then it restarts. I think it is due to overheating. I opened up the back cover to see if the fan thingy is OK. There are two fans, and both are spinning fine.
Not sure why!!

Well, my preliminary assessment is that it is that indexing service that is using my CPU go crazy::: thereby causing the heating.  When it is not indexing, it is not that heated even with my heavy lifting programs running.

So, next time it starts indexing, I need to either kill it. Or, let it do its business till finished, without adding load. But that kinda reminds me of my windows machine which needed to be left for updating the virus/adobe/other updates. Not good feeling!!!
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