Very recently I installed JDK 9 and Apache Cassandra from the official site. But now when I start cassandra in foreground, I get this message:
apache-cassandra-3.11.1/bin$ ./cassandra -f
[0.000s][warning][gc] -Xloggc is deprecated. Will use -Xlog:gc:/home/mmatak/monero/apache-cassandra-3.11.1/logs/gc.log instead.
intx ThreadPriorityPolicy=42 is outside the allowed range [ 0 ... 1 ]
Improperly specified VM option 'ThreadPriorityPolicy=42'
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.
So far I didn't find any solution for this. Is it maybe possible that Java 9 and Cassandra are not yet compatible? Here is that problem mentioned as well - #CASSANDRA-13107
But I am not sure how to just "remove the flag"? Where is it possible to override or remove this flag?
I had exactly the same issue: Can't start Cassandra (Single-Node Cluster on CentOS7)
If it is an option for you, using Java 8, instead of 9, is the simplest way to solve the issue.
@Martin Matak Just comment out that line in the conf/jvm.options file:
########################
# GENERAL JVM SETTINGS #
########################
# allows lowering thread priority without being root on linux - probably
# not necessary on Windows but doesn't harm anything.
# see http://tech.stolsvik.com/2010/01/linux-java-thread-priorities-workaround.html
**#-XX:ThreadPriorityPolicy=42**
Setting the following env variables solved the problem in MAC
export JAVA8_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home
export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home
Theres a jvm.options in your conf directory which sets it:
Solution to your Question
Reason for this exception
- Multiple JDK versions running,probably JDK9,JDK 10 is causing this exception.
- Set the Path to Point JDK 8 Version only.
- Currently cassandra 3.1 is desired to run greater than jdk 8 only.
Change in Cassandra-Conf file (/opt/apache-cassandra-3.11.2/conf/cassandra-env.sh)
4.If you want to use higher JDK Version, update the system path variables based on your OS.
Following from Jay's answer if you're on macOS and installed via Homebrew: the file is located at local/etc/cassandra/jvm.options.
来源：https://stackoverflow.com/questions/46936170/cassandra-and-java-9-threadprioritypolicy-42-is-outside-the-allowed-range