Method jdk8u-dev/jdk/src/share/native/com/sun/java/util/jar/pack/coding.cpp coding::init() 
isn't properly synchronized, in concurrent environment it could lead to exceptions or to unpredictable behavior.


The following exception was observed during JPRT test run:
java.lang.RuntimeException: java.lang.RuntimeException: java.io.IOException: assert failed: !(isFullRange | isSigned | isSubrange)

     at DefaultTimeZoneTest$1.run(DefaultTimeZoneTest.java:115)
Caused by: java.lang.RuntimeException: java.io.IOException: assert failed: !(isFullRange | isSigned | isSubrange)

     at DefaultTimeZoneTest$UnpackAction.run(DefaultTimeZoneTest.java:90)
     at DefaultTimeZoneTest$1.run(DefaultTimeZoneTest.java:113)
Caused by: java.io.IOException: assert failed: !(isFullRange | isSigned | isSubrange)

     at com.sun.java.util.jar.pack.NativeUnpack.start(Native Method)
     at com.sun.java.util.jar.pack.NativeUnpack.run(NativeUnpack.java:198)
     at com.sun.java.util.jar.pack.NativeUnpack.run(NativeUnpack.java:247)
     at com.sun.java.util.jar.pack.UnpackerImpl.unpack(UnpackerImpl.java:138)
     at com.sun.java.util.jar.pack.UnpackerImpl.unpack(UnpackerImpl.java:174)
     at DefaultTimeZoneTest$UnpackAction.run(DefaultTimeZoneTest.java:88)
     ... 1 more

It can be thrown only from one place:
http://ipw83120.uk.oracle.com:8080/source/xref/jdk8u-dev/jdk/src/share/native/com/sun/java/util/jar/pack/coding.cpp#130

The following call chain leads to it:

java NativeUnpack ->
jdk8u-dev/jdk/src/share/native/com/sun/java/util/jar/pack/jni.cpp#Java_com_sun_java_util_jar_pack_NativeUnpack_start
http://ipw83120.uk.oracle.com:8080/source/xref/jdk8u-dev/jdk/src/share/native/com/sun/java/util/jar/pack/jni.cpp
    ->
jdk8u-dev/jdk/src/share/native/com/sun/java/util/jar/pack/unpack.cpp
http://ipw83120.uk.oracle.com:8080/source/xref/jdk8u-dev/jdk/src/share/native/com/sun/java/util/jar/pack/unpack.cpp
    ->
    coding::findBySpec
http://ipw83120.uk.oracle.com:8080/source/xref/jdk8u-dev/jdk/src/share/native/com/sun/java/util/jar/pack/coding.h
http://ipw83120.uk.oracle.com:8080/source/xref/jdk8u-dev/jdk/src/share/native/com/sun/java/util/jar/pack/coding.cpp
    ->
    at the end we get to:
http://ipw83120.uk.oracle.com:8080/source/xref/jdk8u-dev/jdk/src/share/native/com/sun/java/util/jar/pack/coding.cpp#72

Exception happens due lack of synchronization in coding::init, it is assumed to be invoked only once.
At very beginning of method you can find:
>>  if (umax > 0)  return this;  // already done
and at the end:
// do this last, to reduce MT exposure (should have a membar too)
139  this->umax = this_umax;