Code Review Request 7142596: RMI JPRT tests are failing

Darryl Mocek darryl.mocek at
Tue Jul 10 21:14:55 UTC 2012

On 07/09/2012 04:41 PM, Stuart Marks wrote:
> OK, here's the review for the second half of the files in the webrev. 
> I saw your reply to the first half (to which I'll reply separately), 
> and I don't think there's anything here that's affected by them.
> ***
> ***
> REGISTRY_PORT should be a local variable; also rename to use mixed case.
Changed to a private registryPort (see next issue).
> Eh, whoops, after looking at I see that it 
> accesses the REGISTRY_PORT field directly. This is why direct field 
> access is a bad idea. :-) Now the question is, has REGISTRY_PORT been 
> initialized before ApplicationServer needs it? It turns out that it 
> has been -- but only in some cases.
> It seems like the test is trying to support two modes, one that runs 
> in two threads in the same JVM, and the other that runs in two 
> separate JVMs. If they are in separate JVMs, things will no longer 
> work because in the JVM that runs ApplicationServer.main(), 
> AppleUserImpl.REGISTRY_PORT will be -1. I suspect that our test 
> environment doesn't support the separate JVM mode, but it seems unwise 
> to break it.
> I'd suggest that in two-JVM mode the classes fall back to using a 
> "well-known" default registry port number, which in this case seems 
> like 2006.
> In single-JVM mode, AppleUserImpl creates an instance of 
> ApplicationServer, so I'd suggest adding a method to ApplicationServer 
> that allows AppleUserImpl to store the randomly-assigned registry port 
> number into it, overriding the default value.
> This seems like this is the simplest way to preserve the two modes of 
> operation but to support the random port selection model we're trying 
> to achieve.
Rather then going the "fixed port" route, which is what we're trying to 
get away from, I've changed the implementation of both AppletUserImpl's 
and ApplicationServer so ApplicationServer requires a port and 
AppleUserImpl supplies the port on construction of ApplicationServer.  I 
thought of modifying ApplicationServer's constructor to create a port 
using TestLibrary.getUnusedRandomPort, but decided requiring a port is 
better as ApplicationServer's job is to look for already exported 
AppleUser objects.
> *** activatable/
>     int registryPort = new 
> Integer(System.getProperty("rmi.registry.port"));
> I'd suggest using Integer.parseInt() instead of new Integer(). Not a 
> huge deal, but it's probably more conventional to use parseInt() and 
> it avoids boxing.
> One could probably do Integer.getInteger("rmi.registry.port") but this 
> is seems pretty obscure to me even though it's more succinct.
> The same also applies to the following:
>  -
>  - unicast/
>  -
>  -
>  -
>  -
>  - dgcDeadLock/
Integer.parseInt returns a primitive (which is what the return is 
assigned to) and it appears Integer.parseInt is "faster" then creating a 
new Integer.  Changed to Integer.parseInt in all places referenced.
> ***
> The pattern here is a bit odd, as the test creates the registry, 
> throws away the returned reference, and then calls getRegistry() to 
> get another Registry reference. It *seems* like they're identical 
> references, but in fact the first is apparently a reference to the 
> actual Registry implementation, whereas the second is a remote stub.
> The tests seem to do all the actual work using the remote stub, which 
> seems proper.
> This is confusing, though, as it looks like there's a redundant 
> Registry reference now. This might lead someone in the future to 
> "simplify" the test by not getting the remote stub, which in turn 
> might invalidate some tests. (In fact I was going to suggest this but 
> I decided to investigate further first.)
> At the very least, I'd suggest renaming the variable that holds the 
> newly created Registry to something like "registryImpl" to make it 
> clear that it's different from the thing returned by getRegistry(), 
> even though they have a the same time.
> Another possibility is to rearrange the TestLibrary API so that there 
> is a single utility method that combines createRegistryOnUnusedPort() 
> and getRegistryPort(). That is, it creates a new registry and simply 
> returns the port on which it was created, not a reference to the 
> registry implementation.
> I don't think the registry implementation is actually ever used by the 
> tests, and it might simplify things a bit as well.
> Possibly similar issues with:
>  -
>  -
> ***
> Unnecessary call to TestLibrary.getUnusedRandomPort()?
Looks like extra code left over from the change from using 
TestLibrary.getUnusedRandomPort/LocateRegistry.createRegistry(randomPort) to 
> ***
> Mostly pretty straightforward, but I do have some concerns about the 
> random port selection and a potential clash with the "reserved port 
> range" as defined in this test library.
> The getUnusedRandomPort() method attempts to get a socket within the 
> range (1024,64000) and will retry 10 times if it can't. Unfortunately, 
> MacOS allocates ports more-or-less sequentially in the range [49152, 
> 65536) which means that when the kernel's internal counter gets to 
> 64000, getUnusedRandomPort()'s retries will fail, causing tests to 
> fail until the counter wraps around.
> Other systems behave differently; Linux seems to allocate them 
> randomly in the range [32768,65536) and Windows XP SP3 allocates them 
> sequentially in the range (1024,5000]. So it's probably not a problem 
> for them.
> I think the thing to do is to check only for "reserved ports" that are 
> actually used by tests here. These are in the range [64001,64005]. In 
> getUnusedRandomPort(), it should only need to retry if the returned 
> port is within this narrow, reserved range. If it's anything else it 
> should be OK.
I'll try setting the range this narrow, but I don't know how many 
sequential tests will be run at a time and I'm concerned 5 is too few.  
The -concurrency option on jtreg allows you to specify how many 
concurrent tests will be run.  We should have enough test ports reserved 
to satisfy any concurrency request.  I've run the tests with 
-concurrency=8 (I have a dual-core system showing 4 CPU's).  I tried 
reducing the port range to 64001/64002 and concurrency=4 and all passed 
fine, so maybe we're OK with just 5.
> On another topic, the three utility methods here:
>  - createRegistryOnUnusedPort
>  - getRegistryPort
>  - getUnusedRandomPort
> all catch exceptions and then return illegal values (null or -1), 
> sometimes after printing some diagnostic information. The problem is 
> that the caller will attempt to soldier on with the illegal return 
> value and will stumble over something later, such as 
> NullPointerException or IllegalArgumentException. This will probably 
> be obvious but it's equally likely to be confusing.
> Since these utilities are all called from test code, and the tests are 
> relying on them to return valid results, I'd suggest just throwing 
> exceptions from the utility methods if they fail. This will (should) 
> cause the test to error out, but that's OK, as it never could have 
> succeeded anyway if the utility call had failed.
I already modified createRegistryOnUnusedPort to throw an exception as 
part of the MultipleRegistries change.  I'm now throwing a 
RuntimeException for getRegistryPort and getUnusedRandomPort if they fail.

See updated webrev:

> s'marks
> On 7/5/12 2:22 PM, Darryl Mocek wrote:
>> Hello core-libs. Please review this webrev to fix Bugs #7142596 and 
>> 7161503.
>> Webrev can be found here: 
>> This commit fixes concurrency issues with the RMI tests.
>> - Added TestLibrary.createRegistryOnUnusedPort method. This creates an
>> RMIRegistry on an unused port. It will try up to 10 times before 
>> giving up.
>> - Added a TestLibrary.getRegistryPort(Registry) method to get the 
>> port number
>> of the registry.
>> - Changed almost all tests from using hard port numbers to using 
>> random port
>> numbers for running the RMI Registry and RMID.
>> - Removed othervm from those tests which don't need it.
>> - Added parameters for tests which spawn a separate VM to pass RMI 
>> Registry and
>> RMID ports in cases where needed.
>> - Added PropertyPermission to security policy files where needed.
>> - Removed java/rmi and sun/rmi from tests which cannot be run 
>> concurrently.
>> - Added java/rmi/Naming to list of tests which cannot be run 
>> concurrently.
>> Thanks,
>> Darryl

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