Stuart, thank you for you comments, responses are below.
New webrev:
http://cr.openjdk.java.net/~aefimov/8021820/webrev.02/
<http://cr.openjdk.java.net/%7Eaefimov/8021820/webrev.02/>
-Aleksej
On 08/06/2013 05:14 AM, Stuart Marks wrote:
Hi Aleksej,
Thanks for the update. I took a look at the revised test, and there
are still some issues. (I didn't look at the build changes.)
1) System-specific resource limits.
I think the biggest issue is resource limits on the number of open
files per process that might vary from system to system. On my Ubuntu
system, the hard limit on the number of open files is 1,024. The test
opens 1,023 files and then one more for the socket. Unfortunately the
JVM and jtreg have several files open already, and the test crashes
before the openFiles() method completes.
(Oddly it crashes with a NoClassDefFoundError from the main thread's
uncaught exception handler, and then the test reports that it passed!
Placing a try/catch of Throwable in main() or openFiles() doesn't
catch this error. I have no explanation for this. When run standalone
-- i.e., not from jtreg -- the test throws FileNotFoundException (too
many open files) from openFiles(), which is expected.)
On my Mac (10.7.5) the soft limit is 256 files, but the hard limit is
unlimited. The test succeeds in opening all its files but fails
because of the select() bug you're fixing. (This is expected; I didn't
rebuild my JDK with your patch.) I guess the soft limit doesn't do
anything on Mac.
Amazingly, the test passed fine on both Windows XP and Windows 8.
I'm not entirely sure what to do about resource limits. Since the test
is able to open >1024 files on Mac, Windows, and possibly other
Linuxes, it seems reasonable to continue with this approach. If it's
possible to catch the error that occurs if the test cannot open its
initial 1,024 files, perhaps it should do this, log a message
indicating what happened, and consider the test to have passed. I'm
mystified by the uncaught/uncatchable NoClassDefFoundError though.
I wonder if this is a question of test environment required for JTREG
tests: if we'll execute JTREG tests with low value assigned to fd hard
limit (for example 10) we'll see a lot of unrelated test failures. So, I
suggest that we can assume that there is no hard limits set (or at least
default ones, i.e. default fd limit on Ubuntu is 4096) on test machine.
But we should consider test as Failed if test failed to prepare it's
environment because of some external limitations. The JTREG doesn't meet
this criteria (log test as PASS and prints incorrect Exception). To
illustrate it I have repeated your experiments on ubuntu linux: set fd
hard limit to 1024 (ulimit -Hn 1024) and got this error by manual run of
test:
Exception in thread "main" java.io.FileNotFoundException: testfile (Too
many open files)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(FileInputStream.java:128)
at SelectFdsLimit.openFiles(SelectFdsLimit.java:63)
at SelectFdsLimit.main(SelectFdsLimit.java:81)
Seems correct to me.
An by JTREG (also with hard limit set to 1024):
----------messages:(3/123)----------
command: main SelectFdsLimit
reason: User specified action: run main/othervm SelectFdsLimit
elapsed time (seconds): 0.168
----------System.out:(0/0)----------
----------System.err:(5/250)----------
Exception: java.lang.NoClassDefFoundError thrown from the
UncaughtExceptionHandler in thread "MainThread"
STATUS:Passed.
Exception in thread "main"
Exception: java.lang.NoClassDefFoundError thrown from the
UncaughtExceptionHandler in thread "main"
result: Passed. Execution successful
test result: Passed. Execution successful
The results are identical to results mentioned by you. It seems to me
that jtreg doesn't correctly processes such test error (at least it
shouldn't be considered as Pass). And I suggest two ways of resolving it:
1. If we don't have official limitations (or default) on what resources
test can use then we shouldn't do any modifications to test.
2. If there is some limitations that we should honor then we'll need to
figure out what to do with NoClassDefFoundError exception in JTREG.
2) Closing files.
If an exception is thrown while opening the initial set of files, or
sometime during the closing process, the test can still leak files.
One approach would be to keep a data structure representing the
current set of open files, and close them all in a finally-block
around all the test logic, and making sure that exceptions from the
close() call are caught and do not prevent the rest of the files from
being closed.
This seems like a lot of work. Perhaps a more effective approach would
be to run the test in "othervm" mode, as follows:
@run main/othervm SelectFdsLimit
This will cause the test to run in a dedicated JVM, so all files will
be closed automatically when it exits. (It would be good to add a
comment explaining the need for othervm, if you do this.)
main/othervm and comments were added.
3) Port number for sockets.
It's fairly common for tests to fail occasionally because they use
some constant port number that sometimes happens to be in use at the
same time by another process on the system. I have to say, 8080 is a
pretty common port number. :-)
For purposes of this test, you can let the system assign a port. Just
use:
new ServerSocket(0)
Completely agree that 8080 port - bad port for testing =). Changed to 0.
4) Style.
It's probably possible to use the same File object for the test file,
instead of creating new File objects repeatedly.
Agree and corrected.
It might be nice to add a comment explaining the logic of the test,
that SocketTimeoutException is expected, and that failure will be
indicated if the accept() throws SocketException caused by the
underlying mishandling of large fds by select().
Comments were added.
Thanks,
s'marks
On 8/5/13 4:47 AM, Aleksej Efimov wrote:
Alan, Tim,
I have addressed your comments and as a result - new webrev:
http://cr.openjdk.java.net/~aefimov/8021820/webrev.01
The list of changes:
1. The connection to Oracle site is removed (it's not internal, but
anyway it's
better not to rely on availability of external resource in test). In
current
version a server socket is created and accept() method is used for
bug disclosure.
2. The cleanup method is added for closing file streams. The JTREG
successfully
cleaned-up on windows after this modification.
3. common/autoconf/toolchain.m4 untouched, but 'bash
common/autoconf/autogen.sh' was executed to update
generated-configure.sh.
Aleksej
On 07/31/2013 06:35 PM, Tim Bell wrote:
Aleksej, Alan
The change in common/autoconf/toolchain.m4 looks correct to me, and
I think
that is a good place to have it. Remember to run 'bash
common/autoconf/autogen.sh' and check in the generated-configure.sh
files as
part of the changeset.
I didn't look at the test case, but I think Alan has some good points.
Tim
On 07/31/13 06:45 AM, Alan Bateman wrote:
On 31/07/2013 05:18, Aleksej Efimov wrote:
Hi,
Can I have a review for the following problem:
The MACOSX JDK (more precisely - the java.net classes) uses the
select()
system call to wait for different events on sockets fds. And the
default
behaviour for select() on Darwin is to fail when fdset contains
the fd with
id greater than FDSET_SIZE(=1024). Test case in webrev illustrates
this
behavior.
There is at least one solution for it: use -D_DARWIN_UNLIMITED_SELECT
compilation flag for all macosx sources: this won't affect other
parts of
JDK because they are not using select().
Currently, I have added this compilation flag to
common/autoconf/generated-configure.sh and
common/autoconf/generated-configure.sh. I wonder, if there is a
better
place where I can put this flag?
The webrev: http://cr.openjdk.java.net/~aefimov/8021820/webrev.00/
BUG: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8021820
Thanks for looking into this one. The build changes look okay to me
but it's
probably best that someone on build-dev agree to those.
Michael McMahon can probably explain why the net code is using
select for
timed read/accept (I have a vague recollection of there being an
issue with
poll due to the way that it is implemented on kqueue with the
result that it
had to be changed to use select).
I think the test needs re-work. It looks to me that the it attempts to
connect to an Oracle internal site so that's not going to work
everywhere.
In general we don't want the tests to be dependent on hosts that
may or may
not exist (we had tests that used to this in the past but they
caused a lot
of grief). It also looks like the test doesn't close the 1023 files
that it
opens at the start and so I assume this test will always fail on
Windows
when jtreg tries to clean-up.
-Alan.
