Cassandra 启动错误，ThreadPriorityPolicy=42

问题描述

当我尝试启动 Cassandra 时，它向我显示了这样的错误，我已经在 env.sh 中的 conf 文件中进行了更改，该文件也是如此.

When I am trying to start Cassandra it shows me error like this I already did changes in the conf file also in env.sh, the file also.

没有类似类型错误的选项适用于此.

No options of similar type error is working for this.

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.

其他信息

java version "9.0.4"
Java(TM) SE Runtime Environment (build 9.0.4+11)
Java HotSpot(TM) 64-Bit Server VM (build 9.0.4+11, mixed mode)

推荐答案

这是 Cassandra 的一个已知问题 - CASSANDRA-13107.

This is a known issue of Cassandra - CASSANDRA-13107.

在 Java 9 JVM 接受 ThreadPriorityPolicy 的任何整数值之前，而 0 和 1 是唯一的有效值.

Before Java 9 JVM accepted any integer value for ThreadPriorityPolicy, while 0 and 1 were the only valid values.

ThreadPriorityPolicy=1 允许提高线程优先级，但前提是进程以 root 权限启动.当ThreadPriorityPolicy=1时，JVM显式检查 euid=0:

ThreadPriorityPolicy=1 allows to raise thread priorities, but only if the process starts with root privileges. When ThreadPriorityPolicy=1, JVM explicitly checks that euid=0:

static int prio_init() {
  if (ThreadPriorityPolicy == 1) {
    // Only root can raise thread priority. Don't allow ThreadPriorityPolicy=1
    // if effective uid is not root. Perhaps, a more elegant way of doing
    // this is to test CAP_SYS_NICE capability, but that will require libcap.so
    if (geteuid() != 0) {
      if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy)) {
        warning("-XX:ThreadPriorityPolicy requires root privilege on Linux");
      }
      ThreadPriorityPolicy = 0;
    }
  }

注意上面代码中的一个错误(或后门):如果您将 ThreadPriorityPolicy 设置为 0 或 1 以外的其他值，euid 检查将被跳过，但应用程序仍将被允许使用高于正常的优先级.Cassandra 使用了这个后门.

Note a bug (or backdoor) in the above code: if you set ThreadPriorityPolicy to something other than 0 or 1, euid check will be skipped, but the application will be still allowed to use priorities above normal. Cassandra uses this backdoor.

由于 JEP 245 JDK 9 改进了命令行参数验证，因此 ThreadPriorityPolicy 不再接受 0 或 1 以外的值.

As a result of JEP 245 JDK 9 improved command line argument validation, and therefore ThreadPriorityPolicy does not accept values other than 0 or 1 anymore.

编辑%CASSANDRA_HOME%/conf/jvm.options文件:

• 如果您在 Linux 上的 root 下运行 Cassandra，
  将 -XX:ThreadPriorityPolicy=42 替换为 -XX:ThreadPriorityPolicy=1
• 否则删除 -XX:ThreadPriorityPolicy=42 行.

• If you run Cassandra under root on Linux,
  replace -XX:ThreadPriorityPolicy=42 with -XX:ThreadPriorityPolicy=1
• Otherwise remove -XX:ThreadPriorityPolicy=42 line altogether.

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