Errors when using STATS functions

[dkang2]

Describe the bug
I have two relatively small files, there are 48 time steps in one file, and 96 in another. The files have only surface data. While I tried to calculate the STATS such as "mean" or "sum". It successfully generated the display for the first dataset, but when do the same thing for the second dataset (no matter which dataset goes first), it generates the flowing command error messages and stop display the stat.

Exception in thread "AWT-EventQueue-0" java.lang.OutOfMemoryError: Java heap space
at anl.verdi.plot.gui.FastTilePlot.computeStatistics(FastTilePlot.java:1809)
at anl.verdi.plot.gui.FastTilePlot.computeDataRange(FastTilePlot.java:2140)
at anl.verdi.plot.gui.FastTilePlot.actionPerformed(FastTilePlot.java:1092)
at java.desktop/javax.swing.JComboBox.fireActionEvent(JComboBox.java:1294)
at java.desktop/javax.swing.JComboBox.setSelectedItem(JComboBox.java:619)
at java.desktop/javax.swing.JComboBox.setSelectedIndex(JComboBox.java:654)
at java.desktop/javax.swing.plaf.basic.BasicComboPopup$Handler.mouseReleased(BasicComboPopup.java:946)
at java.desktop/java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:298)
at java.desktop/java.awt.Component.processMouseEvent(Component.java:6621)
at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3398)
at java.desktop/javax.swing.plaf.basic.BasicComboPopup$1.processMouseEvent(BasicComboPopup.java:551)
at java.desktop/java.awt.Component.processEvent(Component.java:6386)
at java.desktop/java.awt.Container.processEvent(Container.java:2266)
at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:4996)
at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2324)
at java.desktop/java.awt.Component.dispatchEvent(Component.java:4828)
at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4948)
at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4575)
at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4516)
at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2310)
at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2780)
at java.desktop/java.awt.Component.dispatchEvent(Component.java:4828)
at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:775)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:720)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:714)
at java.base/java.security.AccessController.executePrivileged(AccessController.java:778)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:400)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:98)
at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:747)
at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745)
at java.base/java.security.AccessController.executePrivileged(AccessController.java:778)

To Reproduce
Steps to reproduce the behavior:

1. verdi.sh -f /work/MOD3DEV/dkj/Verdi/example_files/WWLLN_12US1_15min_20230801.nc -f /work/MOD3DEV/dkj/Verdi/example_files/WWLLN_12US1_30min_20230801.nc
2. Make Tile Plots for LNT from both datasets
3. Choose either mean or sum from the STATS dropdown manual for each plot
4. See error

Expected behavior
These are relatively small datasets, and I wouldn't think its memory requirement is so large.

Screenshots
Additional error message:
2026.02.19 10:28:01.518 [Thread-2] ERROR anl.verdi.plot.gui.FastTilePlot - Error occurred during computing statistics
java.lang.NullPointerException: Cannot load from object array because "statistics" is null
at gov.epa.emvl.GridCellStatistics.computeStatistics(GridCellStatistics.java:162) ~[?:?]
at anl.verdi.plot.gui.FastTilePlot.computeStatistics(FastTilePlot.java:1851) ~[?:?]
at anl.verdi.plot.gui.FastTilePlot.copySubsetLayerData(FastTilePlot.java:2060) ~[?:?]
at anl.verdi.plot.gui.FastTilePlot.access$14(FastTilePlot.java:2013) ~[?:?]
at anl.verdi.plot.gui.FastTilePlot$5.run(FastTilePlot.java:596) ~[?:?]
at java.lang.Thread.run(Thread.java:1583) [?:?]

[dkang2]

It does seem a memory problem. I tried doubling the JAVAMAXMEM to 12288M and it worked. Just wonder how the STATS calculation takes so large memory. Don't know if there is a more efficient way to do that. The end results of STATS should use less memory.

[lizadams]

Adding these example files to facilitate testing

verdi_example_files_WWLLN_12US1.tar.gz

Tested on my MacOS using an older version of VERDI 2.1.5:

verdi -f /Users/lizadams/Downloads/example_files/WWLLN_12US1_15min_20230801.nc -f /Users/lizadams/Downloads/example_files/WWLLN_12US1_30min_20230801.nc

Where
verdi: aliased to /Users/lizadams/downloads/VERDI_2.1.5_20240627/verdi.command

Setting for memory is:
JAVAMAXMEM="-Xmx4096M"

I was able to get the statistics for both files without getting the memory error.

Using top it shows that 4712M of memory is being used. Even when I create multiple tile plots.
top

Processes: 712 total, 3 running, 709 sleeping, 4389 threads                                                                                                                                                     11:12:38
Load Avg: 2.02, 2.14, 2.15  CPU usage: 12.85% user, 3.2% sys, 84.11% idle  SharedLibs: 369M resident, 84M data, 30M linkedit. MemRegions: 245729 total, 5926M resident, 105M private, 1697M shared.
PhysMem: 15G used (4415M wired, 562M compressor), 542M unused. VM: 25T vsize, 4521M framework vsize, 3810500123(4781) swapins, 3823358782(0) swapouts. Networks: packets: 169682738/166G in, 87612446/27G out.
Disks: 233551690/16T read, 183617741/16T written.

PID    COMMAND      %CPU  TIME     #TH    #WQ  #PORTS MEM    PURG   CMPRS  PGRP  PPID  STATE    BOOSTS              %CPU_ME %CPU_OTHRS UID  FAULTS      COW     MSGSENT     MSGRECV     SYSBSD     SYSMACH    CSW
62552  java         99.3  04:16.20 34/1   2    387    4712M  81M    721M   62548 62548 running  *5[70]              0.00000 0.00000    502  2374964     3513    587466      224475      672666+    1041042+   495738+

When I used VERDI_2.2
Version: 2.2 2026-02-15

./verdi.command -f /Users/lizadams/Downloads/example_files/WWLLN_12US1_15min_20230801.nc -f /Users/lizadams/Downloads/example_files/WWLLN_12US1_30min_20230801.nc -s "LNT[2]" -g tile -s "LNT[4]" -g tile

Using VERDI 2.2 I do reproduce the error that Daiwen reported above.

When I change verdi.command to use JAVAMAXMEM="-Xmx12288M", and then used the statistics for both plots, the error goes away.

Top shows that the memory being used is 10G

It seems to take longer to do calculate the stats and redraw the window.
Perhaps there is a memory leak?