陈磊 wrote:
Great. I remember that FileInputStream's constructor also has performance
problem. Maybe it was caused by the same reason.
I guess so. Default, there is no SecurityManager installed, the gap with
RI is not so huge, but still slow five times, need to be optimized.
On Mon, Mar 16, 2009 at 3:33 PM, Regis <[email protected]> wrote:
Regis wrote:
Hi all,
Recently I found our java.io.File implementation is obviously slower than
RI on Windows, especially when a SecurityManager is installed.
Testing with following simple test case:
File file = new File("FilePerTest.java");
long start = System.currentTimeMillis();
for (int i = 0; i < 40000; ++i) {
file.isFile();
file.exists();
file.canRead();
}
long end = System.currentTimeMillis();
hy without SecuirtyManager ri without SecuirtyManager
6766ms 1203ms
after installing a SecuirtyManager
System.setSecurityManager(new SecurityManager());
hy with SecuirtyManager ri with SecuirtyManager
54406ms 4078ms
We can see the gap is huge. After some investigations, I found two
problems in Harmony implemenation:
1. Harmony used File.getCanonicalPath() in FilePermission, which is very
slow. Because if a SecurityManager was installed, every file operation would
be check by FilePermission, that cause the huge gap (54406ms compare to
4078ms).
2. in file native code file.c, ioh_convertToPlatform is called by every
method which "convert all separators to the proper platform separator and
remove duplicates on non POSIX platforms." (copied from comment of method),
that is exactly what File.fixSlashes did, I think they are duplicated.
I have created a JIRA HARMONY-6116 to track this issue, and sub-task
HARMONY-6117 for 1. A prototype patch already attach to HARMONY-6117, your
comments and suggestions are welcome.
After patch HARMONY-6117, I got a great improvement when installed a
SecuirtyManager:
hy: 49922ms
hy with patch: 15547ms
ri: 4250ms
--
Best Regards,
Regis.
--
Best Regards,
Regis.
