On 1/6/2022 2:03 PM, David Smiley wrote:
The new Shenandoah GC looks exciting but may not be sufficiently ready
for us to recommend (if I recall from a recent user who reported a
problem with it) -- and that's okay.
I've done some experiments with Shenandoah and ZGC. My index is tiny,
155297 docs and a total index size of 644.22MB. I'm running it with a
max heap of 512MB.
When I uploaded the GC logs to gceasy, the newer collectors showed much
smaller pauses than G1, and more collections. I think the overall pause
time is significantly smaller, but throughput took a hit. It was a
larger impact than I imagined. Last time I tested it, a full rebuild of
the index took about 8 minutes with G1, and over 9 minutes with the
newer collectors. That index is built and used by my dovecot install.
There's pretty much no query activity on my system, so I used the full
index rebuild to exercise it.
I had a remote co-conspirator on this testing. On that user's index,
their reindex procedure failed to complete at all with the newer
collectors, but it did work with G1. I did not get any details about
how it failed, but I know that their testing and mine were done with
OpenJDK 11.
I was going to do some additional testing with OpenJDK 17.0.1, but I
found that when I tried to start Solr with Shenandoah, it has the
following in the console log:
Error occurred during initialization of VM
Option -XX:+UseShenandoahGC not supported
This is very weird, because I saw an article about sub-millisecond
pauses using OpenJDK 17 and Shenandoah. Unless Oracle has decided to
pull Shenandoah completely in-house and not make it available in OpenJDK
any more.
Thanks,
Shawn
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
