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Hello hps-software,

I have been running some A' events through the lcsim software and have been
running into memory problems.

System Information:
OS: Red Hat Enterprise Linux Server release 5.7 (Tikanga)
RAM: 22 GB

SLCIO File Generation Information:
SLIC: 4.9.6
GEANT4: 9.6.1
Geometry: HPS-Proposal2014-v5-6pt6.lcdd
Input Files: ap6.6gevXXXmev.stdhep
where XXX = { 050, 100, 200, 300, 400, 500, 600 } are the A' masses.

LCSim Information:
hps-java: 1.8
Drivers:
     - EventMarkerDriver
     - CalibrationDriver
     - TestRunTriggeredReconToLcio
     - FADCEcalReadoutDriver
     - EcalRawConverterDriver
     - CTPEcalClusterer
     - FADCTriggerDriver
     - SimpleSvtReadout
     - HPSEcalTriggerPlotsDriver
     - AidaSaveDriver
     - ClockDriver
The steering file is attached for more detailed reference. It is a modified
version of Sho's HPS2014ReadoutToLcio.lcsim.

Problem Manifestation:
When I started running the A' events through LCSim, I got heap errors and
OutOfMemoryErrors. These were intially resolved by including the
-Xmx[Amount] option when running, but for the larger files (>1 GB, >100,000
events) I still received memory errors even when I allotted Java the
entirety of the server's available memory. I was ultimately able to get all
the files to run by downloading them to my personal machine (a Windows
device) and running hps-java there, but it was necessary to allot Java
approximately 55 GB of RAM to accomplish this.

I ran some diagnostics while the LCSim software was running on my local
machine and observed the memory footprint of the software. I found that it
started low, but continually increased throughout the duration of the run.
My guess from what I saw is that the Java virtual machine is not correctly
cleaning old objects from memory, so they are building up causing the large
event files to rapidly expand in memory.

I have attached two log files. The first is from the 2.5 GB A' file for 600
MeV masses. This run was ultimately terminated by me because it reached the
maximum amount of server memory that I could allot it and then froze while
it tried to get more memory. The second log files are from another run
where it did yield an OutOfMemoryError.

Any ideas as to cause of this?

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