该问题是怎么引起的？

-|2021-04-10 18:07:18.467|ERROR||JVMService-consume-3-1|c.c.a.c.jvm.thread.JvmThreadService.run:102-send JVM thread metrics to Collector fail. java.lang.NoClassDefFoundError: com/sun/tools/attach/VirtualMachine at com.cubic.agent.utils.VmUtils.getVirtualMachine(VmUtils.java:22) at com.cubic.agent.cmd.jstack.CommandExecutor.execute(CommandExecutor.java:33) at com.cubic.agent.cmd.jvm.thread.ThreadProvider.getThreadDump(ThreadProvider.java:67) at com.cubic.agent.cmd.jvm.thread.JvmThreadService$Sender.run(JvmThreadService.java:87) at com.cubic.agent.cmd.jvm.thread.RunnableWithExceptionProtection.run(RunnableWithExceptionProtection.java:21) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at com.cubic.agent.dependencies.io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) at java.lang.Thread.run(Thread.java:748)