Strange Issue With Static Global Variable in Native

[Dan Xu]

On 12/07/2013 02:57 AM, Alan Bateman wrote:
> On 07/12/2013 01:22, Dan Xu wrote:
>> Hi All,
>>
>> When working on 
>> src/solaris/native/sun/net/spi/DefaultProxySelector.c, previously I 
>> tried to cached a jobject (The cached java object is 
>> java.net.Proxy.NO_PROXY, which is a special type of Proxy.) as a 
>> global static variable, no_proxy, in this c file. Its value is 
>> initialized in the init() native function call. In the following 
>> proxy query by calling native function, getSystemProxy(), I will just 
>> return this no_proxy object if no proxy is found.
>>
>> But strangely, in the case that I return this no_proxy object back to 
>> java side, the program may throw an ClassCastException saying that 
>> the object that is passed to java side is a java.io.FileDescriptor 
>> instead of a java.net.Proxy. The problem only happened in jprt in 
>> test, java/net/ProxySelector/MultiThreadedSystemProxies.java. If I 
>> test it in my local linux, it seems always passed.
>>
>> In addition, instead of caching this special proxy object, I modified 
>> my change to create no_proxy jobject every time I need by using the 
>> same code that I previously used to create no_proxy in the init() 
>> function. And the change can pass the jprt test without any issue. 
>> Does anyone know why the cached proxy object changed to a 
>> FileDescriptor? Thanks!
>>
>> -Dan
> Just so I understand, did you use a JNI global when caching the reference?
>
> -Alan
Hi Alan,

What is a JNI global? What I use here is a static global variable. I 
have uploaded this file to 
http://cr.openjdk.java.net/~dxu/8025437/DefaultProxySelector1.c. You can 
search for "no_proxy". I have declared this variable as "static jobject' 
at the beginning, and initialized it in function initJavaClass().

The error message can be found at 
http://prt-web.us.oracle.com//archive/2013/12/2013-12-07-173617.dan.jdk8Repo4/logs/linux_x64-product-c2-jdk_net.log.FAILED.log

Thanks!

-Dan


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