我们正在用jvm8版本运行tomcat9。我们将最小堆设置为2gb，最大为7gb。但是我们经常看到本机内存分配（mmap）失败的错误。堆配置看起来像： "-Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Xms2048M -Xmx7168M -XX:MaxPermSize=512M" 我能看出在失败之前有足够的堆那么它为什么失败。我们的系统vm.max\u map\u count

sysctl vm.max_map_count
vm.max_map_count = 65530

免费-总共使用了免费共享buff/cache可用内存：52187 19653 452 40 32082 32012交换：4095 80 4015。
我观察到os vm.max\u map也在不断增加，通常在linux上默认大小是65k左右。昨天是8k（tomcat重启时），现在增加到25k

pmap 46012|wc -l
33410
# There is insufficient memory for the Java Runtime Environment to continue.
# Native memory allocation (mmap) failed to map 12288 bytes for committing reserved memory.
# Possible reasons:
# The system is out of physical RAM or swap space
# In 32 bit mode, the process size limit was hit
# Possible solutions:
# Reduce memory load on the system
# Increase physical memory or swap space
# Check if swap backing store is full
# Use 64 bit Java on a 64 bit OS
# Decrease Java heap size (-Xmx/-Xms)
# Decrease number of Java threads
# Decrease Java thread stack sizes (-Xss)
# Set larger code cache with -XX:ReservedCodeCacheSize=
# This output file may be truncated or incomplete.
# 
# Out of Memory Error (os_linux.cpp:2627), pid=51706, tid=0x00007f403bbbf700
# 
# JRE version: Java(TM) SE Runtime Environment (8.0_102-b14) (build 1.8.0_102-b14)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.102-b14 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 (0x00007f48d9131800):  JavaThread "CBONLINE-DBAdapter-DB-Pool connection closer" daemon [_thread_new, id=68713, stack(0x00007f403babf000,0x00007f403bbc0000)]
Stack: [0x00007f403babf000,0x00007f403bbc0000],  sp=0x00007f403bbbe9a0,  free space=1022k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.so+0xac52aa]  VMError::report_and_die()+0x2ba
V  [libjvm.so+0x4fc29b]  report_vm_out_of_memory(char const*, int, unsigned long, VMErrorType, char const*)+0x8b
V  [libjvm.so+0x922603]  os::Linux::commit_memory_impl(char*, unsigned long, bool)+0x103
V  [libjvm.so+0x9226cc]  os::pd_commit_memory(char*, unsigned long, bool)+0xc
V  [libjvm.so+0x91c17a]  os::commit_memory(char*, unsigned long, bool)+0x2a
V  [libjvm.so+0x92089f]  os::pd_create_stack_guard_pages(char*, unsigned long)+0x7f
V  [libjvm.so+0xa6a55e]  JavaThread::create_stack_guard_pages()+0x5e
V  [libjvm.so+0xa73d44]  JavaThread::run()+0x34
V  [libjvm.so+0x9249c8]  java_start(Thread*)+0x108
C  [libpthread.so.0+0x7ea5]  start_thread+0xc5
---------------  P R O C E S S  ---------------
Java Threads: ( => current thread )
  0x00007f48d9132800 JavaThread "DBAdapter-DB-Pool connection adder" daemon [_thread_new, id=68714, stack(0x00007f4035156000,0x00007f4035257000)]
=>0x00007f48d9131800 JavaThread "DBAdapter-DB-Pool connection closer" daemon [_thread_new, id=68713, stack(0x00007f403babf000,0x00007f403bbc0000)]
  0x00007f4914add000 JavaThread "AS40
OS:Oracle Linux Server release 7.9
uname:Linux 3.10.0-1160.2.2.el7.x86_64 #1 SMP Thu Oct 22 09:10:02 PDT 2020 x86_64
libc:glibc 2.17 NPTL 2.17 
rlimit: STACK 8192k, CORE 0k, NPROC 160274, NOFILE 65535, AS infinity
load average:4.07 5.27 5.04
/proc/meminfo:
MemTotal:       41053988 kB
MemFree:          353240 kB
MemAvailable:   18211824 kB
Buffers:               0 kB
Cached:         17371124 kB
SwapCached:        30176 kB
Active:         27419984 kB
Inactive:        9387136 kB
Active(anon):   17764840 kB
Inactive(anon):  1767940 kB
Active(file):    9655144 kB
Inactive(file):  7619196 kB
Unevictable:       12380 kB
Mlocked:           12380 kB
SwapTotal:       4194300 kB
SwapFree:        3862524 kB
Dirty:             18944 kB
Writeback:             0 kB
AnonPages:      19420940 kB
Mapped:            76264 kB
Shmem:             85784 kB
Slab:            1544296 kB
SReclaimable:    1019240 kB
SUnreclaim:       525056 kB
KernelStack:      757520 kB
PageTables:       138316 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:    24721292 kB
Committed_AS:   65627724 kB
VmallocTotal:   34359738367 kB
VmallocUsed:      296108 kB
VmallocChunk:   34359310332 kB
Percpu:            28672 kB
HardwareCorrupted:     0 kB
AnonHugePages:  12632064 kB
CmaTotal:              0 kB
CmaFree:               0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:      341824 kB
DirectMap2M:     8046592 kB
DirectMap1G:    35651584 kB

解决这个问题的闲置解决方案是什么？