Hi Ralf,
- diagnosticCommand.cpp You can use `DCmdArgument<jlong>` for -gz option. If you want to use lesser type (e.g. int, unsigned char), I guess you need to modify GenDCmdArgument class. - heapDumper.cpp _nr_of_threads, _id_to_write, _current in CompressionBackend should be added `volatile` at least. (Other values need to be checked) BTW how much processing time is different between single threaded and multi threaded? Also I want to know what number is set to ParallelGCThreads. ParallelGCThreads seems to affect to thread num for GZip compression. Thanks, Yasumasa On 2020/02/07 21:14, Schmelter, Ralf wrote:
Hi everyone, this change adds the option to write a hprof heap dump directly gzipped. Currently this is supported for the GC.heap_dump diagnostic command via the “-gz” flag. Since gzip is not particular fast when compressing the data, the actual compression will be done parallel in a bunch of background threads. The created file itself is not a single gzip stream, but a concatenation of streams of about 1 MB gzippped data. This makes it easier to parallelize the compression and it allows for an at least semi-efficient random access to the created file. I’ve adjusted the jhat library to be able to directly parse a such a gzipped hrpof file, without the need of prior decompression. bugreport: https://bugs.openjdk.java.net/browse/JDK-8237354 webrev: http://cr.openjdk.java.net/~rschmelter/webrevs/8237354/webrev.0/ If this get reviewed, a CSR is still needed for the change to the GC.heap_dump command. Best regards, Ralf
