Thank you for taking a look! It is indeed. I also tested the same logic on Win JDK 11 and Mac OS X JDK 1.8. The overall pattern is the same: the initial run is super slow (7 seconds on Mac and 1.5 seconds on Win), subsequent runs are dramatically better (down to 150-200 ms on both systems).
On Fri, May 20, 2022 at 10:47 AM PJ Fanning <fannin...@yahoo.com.invalid> wrote: > Is this related to > https://stackoverflow.com/questions/72310943/poi-single-vs-multithreaded-performance > ? > > > > > > > On Friday 20 May 2022, 15:41:28 IST, Wabi Sabi <wabisabi2...@gmail.com> > wrote: > > > > > > Hello, > > I am trying to parallelize Excel processing and I am noticing a > bizarre behavior - single threaded processing is actually faster... > > I am not doing anything fancy. I just open an XSSFWorkbook, fill out some > values, run formula calcs and read the output. If I run single threaded - > initial run takes a few seconds to complete (assume because JVM needs to > load POI + all the XML, schemas, etc.), but performance improves > and subsequent runs all take about 100-200 ms. > > Same logic executed in a separate thread runs easily for 5 seconds in each > thread.... So turns out that single threaded processing of say 10 files is > at 4.5 seconds, but multithreaded takes 5-6 easily... No files are shared > among threads. > > The hotspots are in POIXMLDocument.load. Thread behavior also looks > correct. File contention is out of the picture too - reading a different > file each time. > > Any ideas as two why or pointers at the POI multithreading best practices > are greatly appreciated. Thank you very much in advance! > > --------------------------------------------------------------------- > To unsubscribe, e-mail: user-unsubscr...@poi.apache.org > For additional commands, e-mail: user-h...@poi.apache.org > >
