PING: RFR: 8205992: jhsdb cannot attach to Java processes running in Docker containers

[Jini George]

Hi Yasumasa,

This looks good to me except for one nit. And some more comments would 
help. For e.g., it would help to say that NSPidMap is to map the host to 
container lwpids.

The nit:

* 
http://cr.openjdk.java.net/~ysuenaga/JDK-8205992/webrev.00/src/jdk.hotspot.agent/linux/native/libsaproc/LinuxDebuggerLocal.c.sdiff.html
Line 253: extra space after the parentheses

Thanks,
Jini.

On 7/4/2018 4:34 AM, Yasumasa Suenaga wrote:
> PING: Could you review it?
> 
>>   JBS:    https://bugs.openjdk.java.net/browse/JDK-8205992
>>   webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8205992/webrev.00/
> 
> 
> Thanks,
> 
> Yasumasa
> 
> 
> On 2018/06/28 22:12, Yasumasa Suenaga wrote:
>> Hi all,
>>
>> Please review this change.
>>
>>   JBS:    https://bugs.openjdk.java.net/browse/JDK-8205992
>>   webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8205992/webrev.00/
>>
>> I tried to attach jhsdb to java process in docker container from 
>> container host, but it couldn't.
>> jcmd supports PID namespace in JDK-8193710, but jhsdb hasn't yet.
>>
>> SA gets LWP ID via thread stack and funcs in libthread_db.so, but they 
>> returns PIDs in container - they are different from host's PID. So I 
>> added the code to scan /proc/<PID>/task to get all LWP IDs and they 
>> are kept in a Map in LinuxDebuggerLocal.
>>
>> Also SA_ALTROOT is set to /proc/<PID>/root if SA detects debuggee runs 
>> in container. It helps SA to parse binaries in container.
>>
>> This change has been pushed to submit repo, and it was failed on OS X 
>> (mach5-one-ysuenaga-JDK-8205992-20180628-1015-28963).
>> But I guess it causes JDK-8205906. This change affects to Linux only.
>>
>> Could you review it?
>>
>>
>> Thanks,
>>
>> Yasumasa
>>