Java 8 在使用内存爆了以后会发生什么？hs_err_pid 日志如何看？

问题：
    Java进程被终止了，然后在应用的目录中发现了hs_err_pid日志。

运维反馈，结论是内存不够了

之前一直运行没有问题，没什么新增访问量，为什么会内存溢出，进程被killer掉类？

1.第一反应看日志：

hs_err_pid，内容如下：

#
# There is insufficient memory for the Java Runtime Environment to continue.
# Native memory allocation (mmap) failed to map 65536 bytes for committing reserved memory.
# Possible reasons:
#   The system is out of physical RAM or swap space
#   The process is running with CompressedOops enabled, and the Java Heap may be blocking the growth of the native heap
# Possible solutions:
#   Reduce memory load on the system
#   Increase physical memory or swap space
#   Check if swap backing store is full
#   Decrease Java heap size (-Xmx/-Xms)
#   Decrease number of Java threads
#   Decrease Java thread stack sizes (-Xss)
#   Set larger code cache with -XX:ReservedCodeCacheSize=
#   JVM is running with Unscaled Compressed Oops mode in which the Java heap is
#     placed in the first 4GB address space. The Java Heap base address is the
#     maximum limit for the native heap growth. Please use -XX:HeapBaseMinAddress
#     to set the Java Heap base and to place the Java Heap above 4GB virtual address.
# This output file may be truncated or incomplete.
#
#  Out of Memory Error (os_linux.cpp:2798), pid=15490, tid=0x00007f47859bc700
#
# JRE version: OpenJDK Runtime Environment (8.0_262-b10) (build 1.8.0_262-b10)
# Java VM: OpenJDK 64-Bit Server VM (25.262-b10 mixed mode linux-amd64 compressed oops)
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#

---------------  T H R E A D  ---------------

Current thread (0x00007f47b4196800):  JavaThread "C2 CompilerThread0" daemon [_thread_in_vm, id=15500, stack(0x00007f47858bd000,0x00007f47859bd000)]

Stack: [0x00007f47858bd000,0x00007f47859bd000],  sp=0x00007f47859b85a0,  free space=1005k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.so+0xb5718d]  VMError::report_and_die()+0x15d
V  [libjvm.so+0x50675a]  report_vm_out_of_memory(char const*, int, unsigned long, VMErrorType, char const*)+0xaa
V  [libjvm.so+0x93d3f8]  os::pd_commit_memory(char*, unsigned long, unsigned long, bool)+0xd8
V  [libjvm.so+0x93457e]  os::commit_memory(char*, unsigned long, unsigned long, bool)+0x2e
V  [libjvm.so+0xb53d94]  VirtualSpace::expand_by(unsigned long, bool)+0x1b4
V  [libjvm.so+0x61d15c]  CodeHeap::expand_by(unsigned long)+0x6c
V  [libjvm.so+0x48e0e6]  CodeCache::allocate(int, bool)+0x46
V  [libjvm.so+0x4865db]  BufferBlob::create(char const*, int)+0x8b
V  [libjvm.so+0x48b0e1]  CodeBuffer::initialize(int, int)+0x21
V  [libjvm.so+0x951a62]  Compile::init_buffer(unsigned int*)+0x212
V  [libjvm.so+0x959201]  Compile::Output()+0x351
V  [libjvm.so+0x4ae738]  Compile::Code_Gen()+0x4e8
V  [libjvm.so+0x4b23ce]  Compile::Compile(ciEnv*, C2Compiler*, ciMethod*, int, bool, bool, bool)+0x116e
V  [libjvm.so+0x407e88]  C2Compiler::compile_method(ciEnv*, ciMethod*, int)+0x1d8
V  [libjvm.so+0x4b9cb2]  CompileBroker::invoke_compiler_on_method(CompileTask*)+0x8d2
V  [libjvm.so+0x4ba980]  CompileBroker::compiler_thread_loop()+0x510
V  [libjvm.so+0xafe902]  JavaThread::thread_main_inner()+0x212
V  [libjvm.so+0x93a382]  java_start(Thread*)+0xf2
C  [libpthread.so.0+0x7ea5]  start_thread+0xc5

Current CompileTask:
C2:859196826 31212       4       org.hibernate.engine.query.spi.HQLQueryPlan::<init> (382 bytes)

---------------  P R O C E S S  ---------------

Java Threads: ( => current thread )

用jcmd  -l 查看JVM 参数如下：

输入：

sudo  -u gitlab-runner jcmd 28102 help

VM.native_memory
ManagementAgent.stop
ManagementAgent.start_local
ManagementAgent.start
VM.classloader_stats
GC.rotate_log
Thread.print
GC.class_stats
GC.class_histogram
GC.heap_dump
GC.finalizer_info
GC.heap_info
GC.run_finalization
GC.run
VM.uptime
VM.dynlibs
VM.flags
VM.system_properties
VM.command_line
VM.version
help

输入：

sudo  -u gitlab-runner jcmd 28102 VM.command_line

VM Arguments:
jvm_args: -Xms1200m -Xmx1200m
java_command: xxx.jar --spring.profiles.active=prod
java_class_path (initial): xxxxxx.jar
Launcher Type: SUN_STANDARD

而物理机的内存为：

3.8G

现在的疑惑是内存在没什么访问的情况下，究竟为什么会内存爆掉？内存泄漏？

（未完待续）