Backtrace for Java thread at early JVM startup - was: Hotspot segfaulting on Linux SPARC

[John Paul Adrian Glaubitz]

Hi!

I am still trying to fix Hotspot on Linux/SPARC and it seems that the
problem is related to a HashMap which is created during VM startup.

 From studying the code, I found that the following exception:

glaubitz at deb4g:/srv/glaubitz/hs$ ./build/linux-sparcv9-normal-server-fastdebug/jdk/bin/java --version
Error occurred during initialization of boot layer
java.lang.module.FindException: Error reading module: /srv/glaubitz/hs/build/linux-sparcv9-normal-server-fastdebug/jdk/modules/java.sql
Caused by: java.lang.module.InvalidModuleDescriptorException: Illegal load factor: -1.2197928E-12
glaubitz at deb4g:/srv/glaubitz/hs$

is thrown in this constructor:

     public HashMap(int initialCapacity, float loadFactor)

in src/java.base/share/classes/java/util/HashMap.java.

Now, if I hard-wire the load factor to the default value of 0.75f:

diff -r 46dc568d6804 src/java.base/share/classes/java/util/HashMap.java
--- a/src/java.base/share/classes/java/util/HashMap.java        Fri Apr 13 14:06:39 2018 +0200
+++ b/src/java.base/share/classes/java/util/HashMap.java        Sun Apr 15 00:48:11 2018 +0300
@@ -448,6 +448,7 @@
          if (initialCapacity < 0)
              throw new IllegalArgumentException("Illegal initial capacity: " +
                                                 initialCapacity);
+       loadFactor = 0.75f;
          if (initialCapacity > MAXIMUM_CAPACITY)
              initialCapacity = MAXIMUM_CAPACITY;
          if (loadFactor <= 0 || Float.isNaN(loadFactor))

the JVM seems to startup normally:

glaubitz at deb4g:/srv/glaubitz/hs$ ./build/linux-sparcv9-normal-server-fastdebug/jdk/bin/java --version
openjdk 11-internal 2018-09-25
OpenJDK Runtime Environment (fastdebug build 11-internal+0-adhoc.glaubitz.hs)
OpenJDK 64-Bit Server VM (fastdebug build 11-internal+0-adhoc.glaubitz.hs, mixed mode)
glaubitz at deb4g:/srv/glaubitz/hs$

Now, in order to figure out what's actually wrong, it would be handy to get
a backtrace of the Java thread to understand where the invalid value for
loadFactor, -1.2197928E-12, comes from.

Any suggestions?

Thanks,
Adrian

-- 
  .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz at debian.org
`. `'   Freie Universitaet Berlin - glaubitz at physik.fu-berlin.de
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