On Sat, 29 Jan 2022 06:51:59 GMT, Thomas Stuefe <stu...@openjdk.org> wrote:
>> Tyler Steele has updated the pull request incrementally with two additional >> commits since the last revision: >> >> - Changes macoss -> macosx in problem list >> - Refactors loadlib_aix: Removes redundant c++ class > > src/hotspot/os/aix/os_perf_aix.cpp line 631: > >> 629: >> net_stats[i].ibytes, >> 630: >> net_stats[i].obytes, >> 631: >> *network_interfaces); > > When looking at NetworkInterface, I saw that it copies the name into its own > resource-area allocated string in the constructor. This is all over the > place, SystemProcess assumes C-heap storage, NetworkInterface uses RA... :( > > The problem now is that your ResourceMark above may also destroy the internal > string in NetworkInterface when the Stack is unwound beyond this function. > > Side note: this is what I don't like about how hotspot uses RA. Its often not > clear which data are RA allocated without looking at the code. In Objective-C > (at least how its used on Mac) they had a clear naming convention for methods > that returned storage from the AutoReleasePool. > > The problem is also that with ResourceMarks cutting off your data, you may > not see the problem until much later. Usually you only see immediate problems > if the underlying arena (a chained list of malloced slabs) added a new slab > under your ResourceMark, which then gets free'd when the ResourceMark goes > out of scope. > > How to fix this: > 1) revert to NEW_C_HEAP_ARRAY for your records array here, with appropriate > cleanup, and remove ResourceMark > 3) Change NetworkInterface class to use C-heap instead. > > I'd opt for (1) since it avoids discussions about changing shared code. I > opened https://bugs.openjdk.java.net/browse/JDK-8280912 to change > NetworkInterface, but don't wait for me. I made the change in (1) as recommended. ------------- PR: https://git.openjdk.java.net/jdk/pull/6885
