Tomcat crashed on Linux when it was unable to successfully map the shared 
spaces (see bug 4959691). The fix for that bug prevents the crash, but
does not explain why the shared space was not allocated.

N/A

  xxxxx@xxxxx   2004-02-04
There are problems with the algorithms used to guess where in the address 
space to place the shared spaces.


  xxxxx@xxxxx   2004-03-09
Tomcat (in this example) uses a 1GB heap:  -Xmx:1024m

The problem can be duplicated simply with
java -Xshare:on -Xmx:1024m -version

See comments.
It's likely that a real fix for this bug would require significant changes for which it's too late in the release cycle: untargetting from Mustang.
Posted Date : 2005-12-20 18:49:51.0

The fix for 6319801 is supported by most modern Linux kernels, and will avoid this issue.  Closing as duplicate.
Posted Date : 2007-10-10 14:47:59.0

I've also run into this problem when specifying a max heap
size along with the -Xshare:on switch.  Instead of a crash
though, I get the following output:

> /usr/java/j2sdk1.5.0_b32c/bin/java -Xshare:on -Xmx128m
-version
An error has occured while processing the shared archive file.
Unable to reserve shared region.
Error occurred during initialization of VM
Unable to use shared archive.

This is with:

> /usr/java/j2sdk1.5.0_b32c/bin/java -version
java version "1.5.0-beta"
Java(TM) 2 Runtime Environment, Standard Edition (build
1.5.0-beta-b32c)
Java HotSpot(TM) Client VM (build 1.5.0-beta-b32c, mixed mode)

This appears to be a regression from an earlier build:

> /usr/java/j2sdk1.5.0alpha/bin/java -Xshare:on -Xmx128m
-version
java version "1.5.0-beta"
Java(TM) 2 Runtime Environment, Standard Edition (build
1.5.0-beta-b31)
Java HotSpot(TM) Client VM (build 1.5.0-beta-b31, mixed mode)

These were both run on:

> uname -a
Linux sparrow 2.4.22-1.2174.nptl #1 Wed Feb 18 16:38:32 EST
2004 i686 i686 i386 GNU/Linux