PING: RFR: 8241439: jdk.NativeLibraryEvent hooks all opened regular files

[Yasumasa Suenaga]

Hi all,

I've sent review request last month, but nobody has reviewed. Could you review it?

>    JBS: https://bugs.openjdk.java.net/browse/JDK-8241439
>    webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8241439/webrev.01/

os::get_loaded_modules_info() has introduced in JDK-8056242, and it says this function is for dll/so/dylibs.
In fact, os::get_loaded_modules_info() uses EnumProcessModules() in Windows.

In Linux, get_loaded_modules_info() depends on /proc/<PID>/maps, so it hooks regular files (e.g. JAR, CDS archive), and hooks multiple memory regions by one shared library.
We should merge same library to one event, and should not hook regular files (not shared library).

All comments are welcome.


Thanks,

Yasumasa


On 2020/04/16 9:30, Yasumasa Suenaga wrote:
> PING: Could you review it?
> 
>    JBS: https://bugs.openjdk.java.net/browse/JDK-8241439
>    webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8241439/webrev.01/
> 
> 
> Yasumasa
> 
> 
> On 2020/04/09 16:00, Yasumasa Suenaga wrote:
>> Hi all,
>>
>> Please review this change:
>>
>>    JBS: https://bugs.openjdk.java.net/browse/JDK-8241439
>>    webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8241439/webrev.00/
>>
>> HotSpot has os::get_loaded_modules_info() to get all loaded native libraries, however it would call callback in twice on same library on Linux. Also it would call callback even if the file is not a library.
>>
>> We can see this problem in jdk.NativeLibrary JFR event as below:
>>
>>
>> ```
>> jdk.NativeLibrary {
>>     startTime = 16:59:06.621
>>     name = "/usr/lib64/libc-2.30.so"
>>     baseAddress = 0x7FDB06ACC000
>>     topAddress = 0x7FDB06AF1000
>> }
>>
>> jdk.NativeLibrary {
>>     startTime = 16:59:06.621
>>     name = "/usr/lib64/libc-2.30.so"
>>     baseAddress = 0x7FDB06AF1000
>>     topAddress = 0x7FDB06C40000
>> }
>>
>>      :
>>
>> ```
>>
>> ```
>> jdk.NativeLibrary {
>>     startTime = 16:59:06.621
>>     name = "/home/ysuenaga/OpenJDK/jdk/build/linux-x86_64-server-fastdebug/images/jdk/lib/server/classes.jsa"
>>     baseAddress = 0x800000000
>>     topAddress = 0x800007000
>> }
>> ```
>>
>> This change uses dl_iterate_phdr() to get them, so these problem has gone.
>>
>>
>> Thanks,
>>
>> Yasumasa