Why Unsafe.defineClass has high CPU usage

An extremely long running request (> 30s) was observed in a Java 8 / SpringBoot/Tomcat Web application. And the lag time will increase with the running time of the program. But the response to most requests is normal. The CPU load at the time of the lag increases to 100% and then drops off on its own after a few minutes.

Threaddumps shows that unsafe.defineClass is hanging

"http-nio-8080-exec-9" #254 daemon prio=5 os_prio=0 tid=0x00007f8a98b4f000 nid=0x2258 runnable [0x00007f89fb0b0000]
   java.lang.Thread.State: RUNNABLE
    at sun.misc.Unsafe.defineClass(Native Method)
    at sun.reflect.ClassDefiner.defineClass(ClassDefiner.java:63)
    at sun.reflect.MethodAccessorGenerator$1.run(MethodAccessorGenerator.java:399)
    at sun.reflect.MethodAccessorGenerator$1.run(MethodAccessorGenerator.java:394)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.reflect.MethodAccessorGenerator.generate(MethodAccessorGenerator.java:393)
    at sun.reflect.MethodAccessorGenerator.generateMethod(MethodAccessorGenerator.java:75)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:53)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.beans.BeanUtils.copyProperties(BeanUtils.java:618)
    at org.springframework.beans.BeanUtils.copyProperties(BeanUtils.java:538)
    at com.haigui.stateaction.action_impl.DisputeSubmit.insertDisputeInfo(DisputeSubmit.java:128)

The pstack outputs the call stack as follows

Thread 70 (Thread 0x7f0a0119f700 (LWP 18563)):
0x00007f0a5f43dlf8 JvmtiEnv: :GetThreadLocalStorage(_jobject*, void**) () from /usr/local/jdkl.8.0_231/jre/lib/amd64/ser..
0x00007f09ffa882b2 in assertTLSValue () from /usr/local/jdkl.8.0_231/j re/Lib/amd64/libinstrument.so
0x00007f09ffa88427 in releaseReentrancyToken () from /usr/local/jdkl.8.0_231/j re/Lib/amd64/libinstrument.so
0x00007f09ffa86044 in transformClassFile () from /usr/local/jdkl.8.0_231/jre/lib/amd64/libinstrument.so
0x00007f09ffa84eef in eventHandlerClassFileLoadHook () from /usr/local/jdkl.8.0_231/jre/lib/amd64/libinstrument.so
0x00007f0a5f461512 in JvmtiClassFileLoadHookPoster:: post_to_env(JvmtiEnv*, bool) () from /usr/local./idkl.8.0_231/i re/lib/am
0x00007f0a5f453a65 in JvmtiExport::post_class_file_load_hook(Symbol*, Handle, Handle, unsigned char**, unsigned char**, Jvm
0x00007f0a5fll964c in ClassFileParser: :parseClassFile(Symbol.*, ClassLoaderData*, Handle, KlassHandle, GrowableArray<Handle> 
0x00007f0a5f722107 in SystemDictionary::resolve_from_stream(Symbol*, Handle, Handle, ClassFilestream*, bool, Thread*) () fr
0x00007f0a5f3d4f33 in jvm_define_class_common(JNIEnv_*, char const*, _jobject*, signed char const*, int, _jobject*, char co
0x0O007f0a5f3d658a in JVM_DefineClass () from /usr/local/jdkl.8.0_231/j re/lib/amd64/server/libivm.so
0x00007f0a5f77ae4b in Unsafe_DefineClass_impl(JNIEnv_*, _jstring*, _jbyteArray*f int, int, [object*, _jobject*) () from /u
0x00007f0a5f77e3b9 in Unsafe_DefineClass () from /usr/local/jdkl.8.0_231/jre/lib/amd64/server/libjvm.so
0x00007f0a492677cb in ?? 0
0x0O007f0a01199d28 in ??()
0x0000000000000000 in ??()