RFR: JDK-8321266: Add diagnostic RSS threshold [v2]

[Thomas Stuefe]

On Tue, 5 Dec 2023 05:49:58 GMT, David Holmes <dholmes at openjdk.org> wrote:

> Hi Thomas,
> 
> I've taken a first pass through this and it seems okay in principle. A number of initial comments/suggestions below.
> 
> Thanks.

Thanks a lot, David!

Makes me happy to see this finds acceptance at least in principle.

I changed:
- get_rss to get_RSS
- removed the "0 means off" text, since I assume passing 0 would be likely a user error. Instead, I also added an error check for percentage = 0.0.
- added a warning if the OS does not support this feature

> src/hotspot/share/runtime/globals.hpp line 1378:
> 
>> 1376:           "If RssLimit is set, interval, in ms, at which the JVM will "     \
>> 1377:           "check the process resident set size."                            \
>> 1378:           range(10, UINT_MAX))                                              \
> 
> Can we actually handle enrolling a periodic task with a UINT_MAX interval?

No, we can't; I'll correct the limit.

> src/hotspot/share/runtime/threads.cpp line 775:
> 
>> 773:   if (RssLimit != nullptr) {
>> 774:     RssWatcher::initialize(RssLimit);
>> 775:   }
> 
> So I think if we are on AIX or regular BSD then we should at least give a warning that the flag will be ignored, and actually ignore it.

Done

> src/hotspot/share/services/rsswatch.hpp line 41:
> 
>> 39: };
>> 40: 
>> 41: #endif // OS_LINUX_RSSWATCH_HPP
> 
> Comment is wrong

fixed

-------------

PR Comment: https://git.openjdk.org/jdk/pull/16938#issuecomment-1840480839
PR Review Comment: https://git.openjdk.org/jdk/pull/16938#discussion_r1415325628
PR Review Comment: https://git.openjdk.org/jdk/pull/16938#discussion_r1415331131
PR Review Comment: https://git.openjdk.org/jdk/pull/16938#discussion_r1415330645