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MATLAB freezes the OS when using java environments: a Fatal Java Exception occurs (Resource temporarily unavailable)

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Totor
Totor on 21 Feb 2021
Commented: Cam Salzberger on 24 Feb 2021
Hi all,
When I close MATLAB after having run a code using java environments (java.awt.Robot & java.awt.event.*), the entire OS (Linux Ubuntu 18.04) freezes and becomes unresponsive. The problem also occurs without closing MATLAB after some time with the code running. It also occurs when un run the code in the terminal with matlab -bash "my_script". MATLAB works perfectly when I don't import java environments.
After reboot, I have the two following log files (matlab_crash_dump.10824-1 & java.log.10824) with a fatal java exception (FATAL ERROR in native method: Nativewindow X11 IOError: Display 0x7ff5114cac10 (:0): Resource temporarily unavailable). It seems to be related to the use of the getPixelColor of the java robot class. You'll find the logs below.
In a simplified version, my code import java classes in a script and then uses them in functions:
%IMPORT JAVA CLASSES
import('java.awt.Robot');
import('java.awt.event.*');
r=Robot();
%FUNCTION
function [status]=my_fun(r)
%Pixels coordinates
x=[300 600 900 1200 1500];
y=[500 500 500 500 500];
%Get pixels color until they are all black (or timeout at 20 s)
t=tic;
status=false;
while toc(t) < 20
RGB=zeros(numel(x),3);
for i=1:numel(x)
RGB(i,:)=[r.getPixelColor(x(i),y(i)).getRed ...
r.getPixelColor(x(i),y(i)).getGreen ...
r.getPixelColor(x(i),y(i)).getBlue];
end
if isequal(RGB,zeros(numel(x),3))
status=true;
break;
end
end
%Add a delay (2 s)
if isequal(status,true)
r.delay(2000);
r.waitForIdle;
end
end
matlab_crash_dump.10824-1
--------------------------------------------------------------------------------
Assertion detected at dim. févr. 21 20:20:38 2021 +0100
--------------------------------------------------------------------------------
Configuration:
Crash Decoding : Disabled - No sandbox or build area path
Crash Mode : continue (default)
Default Encoding : UTF-8
Deployed : false
Desktop Environment : ubuntu:GNOME
GNU C Library : 2.27 stable
Graphics Driver : Unknown hardware
Graphics card 1 : 0x8086 ( 0x8086 ) 0x5917 Version 0.0.0.0 (0-0-0)
Java Version : Java 1.8.0_202-b08 with Oracle Corporation Java HotSpot(TM) 64-Bit Server VM mixed mode
MATLAB Architecture : glnxa64
MATLAB Entitlement ID : 2127504
MATLAB Root : /usr/local/MATLAB/R2020a
MATLAB Version : 9.8.0.1417392 (R2020a) Update 4
OpenGL : hardware
Operating System : Ubuntu 18.04.5 LTS
Process ID : 10824
Processor ID : x86 Family 6 Model 142 Stepping 10, GenuineIntel
Session Key : ea17b098-38b5-4992-b46e-a7ce4e5c8222
Static TLS mitigation : Enabled: Full
Window System : The X.Org Foundation (11906000), display :0
Fault Count: 1
Additional Log Files:
Java Crash Report : /home/victor/hs_error_pid10824.log
Java Log : /home/victor/java.log.10824
Assertion in void {anonymous}::mwJavaAbort() at javainit.cpp line 1395:
Fatal Java Exception. See this file for details: /home/victor/hs_error_pid10824.log
Register State (captured):
RAX = 00007ff54b3df0ec RBX = 00007ff5da60b088
RCX = 000000000000000a RDX = 00007ff5da5ea6a8
RSP = 00007ff5c93361b0 RBP = 00007ff5c9336570
RSI = 00007ff5da5b0bee RDI = 00007ff5c93361c0
R8 = 00007ff5c9336484 R9 = 00007ff5c9336484
R10 = 0000000000000000 R11 = 0000000000000000
R12 = 00007ff5da5fb008 R13 = 00007ff5c9336df0
R14 = 00007ff5b6c94583 R15 = 00007ff5b6c9f4c0
RIP = 00007ff5da50184e EFL = 0000000000000000
CS = 0000 FS = 0000 GS = ff00
Stack Trace (captured):
[ 0] 0x00007ff5da4f8553 /usr/local/MATLAB/R2020a/bin/glnxa64/libmwfl.so+00853331
[ 1] 0x00007ff5da4f874c /usr/local/MATLAB/R2020a/bin/glnxa64/libmwfl.so+00853836 _ZN10foundation4core4diag15stacktrace_base7captureEm+00000028
[ 2] 0x00007ff5da4fd989 /usr/local/MATLAB/R2020a/bin/glnxa64/libmwfl.so+00874889
[ 3] 0x00007ff5da4fdaf0 /usr/local/MATLAB/R2020a/bin/glnxa64/libmwfl.so+00875248
[ 4] 0x00007ff5b6c407ee /usr/local/MATLAB/R2020a/bin/glnxa64/matlab_startup_plugins/jmi/../../../../bin/glnxa64/libmwjmi.so+01415150
[ 5] 0x00007ff5aee8b700 /usr/local/MATLAB/R2020a/sys/java/jre/glnxa64/jre/lib/amd64/server/libjvm.so+09496320
[ 6] 0x00007ff5aec4273b /usr/local/MATLAB/R2020a/sys/java/jre/glnxa64/jre/lib/amd64/server/libjvm.so+07100219
[ 7] 0x00007ff44d5b5c42 /usr/local/MATLAB/R2020a/bin/glnxa64/libnativewindow_x11.so+00011330 NativewindowCommon_FatalError+00000268
[ 8] 0x00007ff44d5b6988 /usr/local/MATLAB/R2020a/bin/glnxa64/libnativewindow_x11.so+00014728
[ 9] 0x00007ff5d24dc95e /usr/lib/x86_64-linux-gnu/libX11.so.6+00264542 _XIOError+00000078
[ 10] 0x00007ff5d24daa41 /usr/lib/x86_64-linux-gnu/libX11.so.6+00256577 _XReply+00001169
[ 11] 0x00007ff4b2b0756d /usr/lib/x86_64-linux-gnu/libXcomposite.so.1+00005485 XCompositeGetOverlayWindow+00000125
[ 12] 0x00007ff54b3c91bb /usr/local/MATLAB/R2020a/sys/java/jre/glnxa64/jre/lib/amd64/libawt_xawt.so+00229819 Java_sun_awt_X11_XRobotPeer_getRGBPixelsImpl+00000411
[ 13] 0x00007ff562c38920 <unknown-module>+00000000
[ 14] 0x00007ff56227de04 <unknown-module>+00000000
java.log.10824
Operating System: Linux 4.15.0-135-generic #139-Ubuntu SMP Mon Jan 18 17:38:24 UTC 2021 x86_64
Processor ID: x86 Family 6 Model 142 Stepping 10, GenuineIntel
Host Name: katla
FATAL ERROR in native method: Nativewindow X11 IOError: Display 0x7ff5114cac10 (:0): Ressource temporairement non disponible
at sun.awt.X11.XRobotPeer.getRGBPixelsImpl(Native Method)
- locked <0x00000000d3fd6a48> (a java.lang.Class for sun.awt.X11.XRobotPeer)
at sun.awt.X11.XRobotPeer.getRGBPixel(XRobotPeer.java:84)
at java.awt.Robot.getPixelColor(Robot.java:395)
- locked <0x00000000d419a130> (a java.awt.Robot)

Answers (1)

Cam Salzberger
Cam Salzberger on 22 Feb 2021
I assume that you are using SSH with X11 forwarding to work with MATLAB on a remote machine? I would recommend against doing that at all. X11 forwarding tends to have deletrious effects on MATLAB. Using VNC to connect to the machine and view the display tends to be more stable.
Also, directly accessing Java like this isn't really a recommended workflow either. Maybe try to find workarounds that use documented MATLAB tools?
-Cam
  2 Comments
Cam Salzberger
Cam Salzberger on 24 Feb 2021
I'm afraid I am not aware of any alternative for programmatically simulating mouse interaction. What is the other application that you are trying to manipulate though? There may be alternatives for interacting with it (e.g. external language interfaces, hardware connectivity, web access, serial communication, etc.).
-Cam

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