High memory usage / leaks was: Best mailing list for JVM embedding

Robert Marcano robert at marcanoonline.com
Thu Jan 24 13:25:49 UTC 2019

On 1/23/19 8:59 AM, Sean Mullan wrote:
> On 1/22/19 8:50 PM, Bernd Eckenfels wrote:
>> I don’t think the launcher is doing this, it is the class loader, 
>> that’s nothing new. You can turn on verbose security debug to see it 
>> in all versions.
> Yes, and it only verifies the signature(s) on the JAR. It doesn't 
> validate the certificate chain.
> --Sean

I noticed that trying to identify the higher memory usage after what 
looks like a big application is loaded. I am doing memory profiling and 
notice JarFile taking more memory that on Java 8. Still need to detect 
the real cause for an independent test case. We probably didn't notice 
this slowdown before because Oracle's JNLP implementation was slow 
enough at startup.

IMHO the class library should not do doing signature checks without 
certificate validation, because it doesn't give any protection if the 
signature is not verified, the only thing it could do now is to detect 
some random bit flips, that maybe the Zip format CRC detect before that. 
With no certificate verification the signature could be replaced by 
anybody with bad intentions.

Maybe adding a constructor flag to URLClassloader to pass to JarFile to 
skip verification and a system property to tell the Java startup code to 
skip verification of java.class.path (just for compatibility with old 
code that expect it to be done). There is precedent of other runtimes 
that added options to disable this, like CLR [1] (Ii not only verified 
signatures, It do CRL/OSCP checks too)

Our new launcher replacing JNLP now do signature verification in native 
code, at download time, and install on a system area (not user home 
directory), so signature verification at application launch is a 
slowdown we want to avoid, but think on another kind of users, those 
deploying to OS Stores (for example Windows Store), why add the slowdown 
of verification when the application is verified by the store client at 
install time?, this could help these situations too.

Note: This can be avoided removing the signatures of all JARs if you 
distribute to an OS store, there are a few libraries that distribute 
their JARs signed (The old Java Help framework comes to my mind right now)


>> -- 
>> https://Bernd.eckenfels.net
>> ________________________________
>> Von: core-libs-dev <core-libs-dev-bounces at openjdk.java.net> im Auftrag 
>> von Robert Marcano <robert at marcanoonline.com>
>> Gesendet: Mittwoch, Januar 23, 2019 2:18 AM
>> An: Alan Bateman
>> Cc: OpenJDK Dev list; core-libs-dev Libs
>> Betreff: Re: High memory usage / leaks was: Best mailing list for JVM 
>> embedding
>> On Tue, Jan 22, 2019, 5:53 AM Alan Bateman <Alan.Bateman at oracle.com 
>> wrote:
>>> On 22/01/2019 4:48 am, Robert Marcano wrote:
>>>>> :
>>>>> So the question now is, why signed jars could affect the memory usage
>>>>> of an application (we aren't doing JAR verification on our custom
>>>>> launcher, yet), just by being on the java.class.path? IIRC the
>>>>> initial application classpath JARs were never verified previously (by
>>>>> the java launcher alone, without JNLP around).
>>>>> Note: Tested with JARs signed with a self signed certificate and with
>>>>> one signed with a private CA. At most, signing the JARs could slow
>>>>> down the start up if it is now expected to these being verified by
>>>>> the java launcher (is it true?) but not higher memory usage and no
>>>>> reductions after a GC cycle but constants heap size increases.
>>> Signed JARs can be expensive to verify, esp. on first usage as the
>>> verification is likely to result in early loading of a lot of security
>>> classes and infrastructure. If you can narrow down the apparently memory
>>> leak to a small test case with analysis to suggest it's a JDK bug then
>>> it would be good to get a bug submitted.
>>> -Alan
>> Greeting. Sure, I will work on a distributable reproduction of the 
>> problem
>> today but it is new to me that the java launcher do JARs verification 
>> now.
>> If it is doing it I doesn't make sense to me, because a self signed or
>> unrecognized CA doesn't trigger a validation error.

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