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I'd like to download Eclipse, but I'm not sure which version to download 32 or 64?

mbp:~ alexus$ uname -a
Darwin 11.1.0 Darwin Kernel Version 11.1.0: Tue Jul 26 16:07:11 PDT 2011; root:xnu-1699.22.81~1/RELEASE_X86_64 x86_64
mbp:~ alexus$ 

According to my output, I have 64 bit OS. From what I understand before 64 bit application will just allows you to access over 4GB memory at once, while 32 bit has limitation of no more then 4 GB. I only have 4GB and I'm pretty sure I wont ever reach 4 GB using Eclipse either, so theoretically it doesn't really matter which one to choose.

But still which one?

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BTW, your memory isn't limited to your physical memory size (4GB) there is virtual memory that can be way larger. – user2775234 Sep 16 '13 at 15:51
up vote 5 down vote accepted

Since you only have 4GB of RAM, it really doesn't matter. What may matter is the JDK version - you would need x86 JDK for Eclipse 32-bit, while x64 Eclipse would need 64-bit JDK.

As indicated by the Eclipse FAQ, you need to choose your JRE properly:

Please note that if you are on a 64-bit system and have a 64-bit JRE installed, you will need to use a 64-bit Eclipse build. If you wish to use a 32-bit Eclipse build, please use a 32-bit JRE. Mismatches will cause Eclipse to not start properly.

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If you have a 64 bit OS, use the 64 bit version.

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Could you perhaps explain why he should be using 64bit over 32bit though? – Simon Sheehan Sep 1 '11 at 0:09

Java is 64-bit only on the Mac, starting with Java 6. (There's talk of back-porting, but apparently it's not a priority.) Lion also requires a 64-bit CPU. So you're running a 64-bit kernel, on a 64-bit machine, with a 64-bit JRE. Use 64-bit Eclipse.

You may have only 4GB now, but if you upgrade the RAM or get a whole new machine with more, you may have less to reinstall. Unless you have a specific reason to go 32-bit, it's time to leave that old tech behind across the board.

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