请帮忙解释一下OOM-Killer

请帮忙解释一下OOM-Killer

我们正在测试我们的 java 应用程序,它被 OOM Killer 杀死了,日志如下。

几点:这是一个 Java Web 应用程序。它使用 190G 堆运行。服务器是一个总内存为 240G 的 EC2 实例。我们正在尝试 JDK 11 中新的实验性 ZGC。当时应用程序没有负载,在类似产品的测试环境中运行。该应用程序确实有一些由计划触发的处理,并且可能占用大量内存和 CPU,但这些处理经常运行并且没有失败。

应用程序代码与我们生产中的代码相比没有太大变化。我们也成功进行了负载测试,包括 12 小时浸泡测试,没有出现问题。

现在来看看 OOM-Killer 日志。完整日志如下,但有一件事我觉得很奇怪,那就是这一行:

Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.571217] Killed process 4973 (java) total-vm:17181703924kB, anon-rss:9740kB, file-rss:0kB, shmem-rss:0kB

总虚拟机大小约为 17 TB。这对我来说很奇怪,因为我们的应用程序根本不可能正常地尝试请求这个。我怀疑我们可能遇到了一些 ZGC 或 ZGC+我们的代码错误,但我想确保我读得正确。

我非常感谢任何帮助,完整的日志可供参考:

Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.158902] java invoked oom-killer: gfp_mask=0x14200ca(GFP_HIGHUSER_MOVABLE), nodemask=(null),  order=0, oom_score_adj=0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.166556] java cpuset=/ mems_allowed=0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.168975] CPU: 15 PID: 4974 Comm: java Not tainted 4.14.55-62.37.amzn1.x86_64 #1
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.173353] Hardware name: Xen HVM domU, BIOS 4.2.amazon 08/24/2006
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.177219] Call Trace:
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.178806]  dump_stack+0x5c/0x82
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.180848]  dump_header+0x94/0x21c
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.183087]  ? get_page_from_freelist+0x525/0xba0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.185945]  oom_kill_process+0x213/0x410
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.188518]  out_of_memory+0x296/0x4c0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.190748]  __alloc_pages_slowpath+0x9ef/0xdd0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.193653]  __alloc_pages_nodemask+0x207/0x220
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.196455]  alloc_pages_vma+0x7c/0x1e0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.198924]  shmem_alloc_page+0x65/0xa0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.201277]  ? __radix_tree_insert+0x35/0x1f0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.204022]  ? __vm_enough_memory+0x23/0x130
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.206639]  shmem_alloc_and_acct_page+0x72/0x1b0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.209513]  shmem_getpage_gfp+0x14b/0xb40
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.212102]  ? __set_page_dirty+0xc0/0xc0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.214705]  shmem_fallocate+0x32d/0x440
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.217182]  vfs_fallocate+0x13f/0x260
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.219525]  SyS_fallocate+0x43/0x80
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.221657]  do_syscall_64+0x67/0x100
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.223944]  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.227002] RIP: 0033:0x7fcc064ab1f9
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.229295] RSP: 002b:00007fcc071df800 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.233706] RAX: ffffffffffffffda RBX: 0000002f80000000 RCX: 00007fcc064ab1f9
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.237896] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.242203] RBP: 00007fcc071df860 R08: 0000000000000005 R09: 0000000000000000
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.246538] R10: 0000002f80000000 R11: 0000000000000246 R12: 0000000000001000
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.250675] R13: 0000002f80000000 R14: 00007fcc00030d18 R15: 0000002f80000000
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.254948] Mem-Info:
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.256313] active_anon:46337469 inactive_anon:15816944 isolated_anon:0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.256313]  active_file:362 inactive_file:1424 isolated_file:0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.256313]  unevictable:0 dirty:87 writeback:0 unstable:0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.256313]  slab_reclaimable:146831 slab_unreclaimable:12432
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.256313]  mapped:49788503 shmem:61099090 pagetables:297088 bounce:0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.256313]  free:264623 free_pcp:31 free_cma:0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.276739] Node 0 active_anon:185857908kB inactive_anon:62759744kB active_file:1448kB inactive_file:5696kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:199154012kB dirty:348kB writeback:0kB shmem:244396360kB shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 0kB writeback_tmp:0kB unstable:0kB all_unreclaimable? yes
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.293799] Node 0 DMA free:15904kB min:4kB low:16kB high:28kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15988kB managed:15904kB mlocked:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.308882] lowmem_reserve[]: 0 1928 245809 245809
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.311710] Node 0 DMA32 free:976000kB min:528kB low:2500kB high:4472kB active_anon:0kB inactive_anon:1017428kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:2080768kB managed:1995880kB mlocked:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.327796] lowmem_reserve[]: 0 0 243881 243881
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.330558] Node 0 Normal free:66588kB min:67048kB low:316780kB high:566512kB active_anon:187190988kB inactive_anon:60409332kB active_file:1448kB inactive_file:5696kB unevictable:0kB writepending:0kB present:253755392kB managed:249734404kB mlocked:0kB kernel_stack:7280kB pagetables:1188352kB bounce:0kB free_pcp:124kB local_pcp:120kB free_cma:0kB
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.348446] lowmem_reserve[]: 0 0 0 0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.350789] Node 0 DMA: 0*4kB 0*8kB 0*16kB 1*32kB (U) 2*64kB (U) 1*128kB (U) 1*256kB (U) 0*512kB 1*1024kB (U) 1*2048kB (M) 3*4096kB (M) = 15904kB
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.358404] Node 0 DMA32: 1*4kB (M) 1*8kB (U) 2*16kB (UM) 2*32kB (UE) 1*64kB (U) 1*128kB (U) 2*256kB (UE) 3*512kB (UME) 3*1024kB (UME) 2*2048kB (UM) 236*4096kB (M) = 976172kB
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.367499] Node 0 Normal: 2527*4kB (UME) 778*8kB (UME) 293*16kB (UME) 104*32kB (UME) 51*64kB (UME) 24*128kB (UME) 5*256kB (UM) 2*512kB (UM) 1*1024kB (U) 3*2048kB (UME) 8*4096kB (M) = 72924kB
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.377787] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=1048576kB
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.382919] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.387847] 61100730 total pagecache pages
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.390368] 0 pages in swap cache
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.392264] Swap cache stats: add 0, delete 0, find 0/0
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.395429] Free swap  = 0kB
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.397195] Total swap = 0kB
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.398971] 63963037 pages RAM
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.400873] 0 pages HighMem/MovableOnly
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.403102] 1026490 pages reserved
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.405255] [ pid ]   uid  tgid total_vm      rss nr_ptes nr_pmds swapents oom_score_adj name
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.410245] [ 2730]     0  2730     2833      194      11       3        0         -1000 udevd
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.415382] [ 2848]     0  2848     2812      165      10       3        0         -1000 udevd
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.420563] [ 2849]     0  2849     2812      161      10       3        0         -1000 udevd
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.425740] [ 3137]     0  3137    27285       57      21       3        0             0 lvmetad
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.430993] [ 3146]     0  3146     6799       48      18       3        0             0 lvmpolld
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.436187] [ 3354]     0  3354     2353      121      10       3        0             0 dhclient
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.441499] [ 3410]     0  3410    13251       98      27       3        0         -1000 auditd
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.446792] [ 3431]     0  3431    61878      132      23       3        0             0 rsyslogd
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.452140] [ 3451]     0  3451    23291      114      15       3        0             0 irqbalance
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.457538] [ 3461]     0  3461     1630       25       9       3        0             0 rngd
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.462533] [ 3478]    81  3478     5461       58      15       3        0             0 dbus-daemon
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.468050] [ 3513]     0  3513     1099       35       8       3        0             0 acpid
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.473222] [ 3609]     0  3609    20134      207      42       3        0         -1000 sshd
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.478262] [ 3622]     0  3622    28967      266      60       3        0             0 sshd
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.483118] [ 3624]   500  3624    28967      265      59       3        0             0 sshd
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.488272] [ 3625]   500  3625    28850      113      13       3        0             0 bash
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.493403] [ 3658]    38  3658    29129      204      29       3        0             0 ntpd
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.498490] [ 3702]     0  3702    22395      432      45       3        0             0 sendmail
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.503845] [ 3712]    51  3712    20259      374      40       3        0             0 sendmail
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.509091] [ 3724]     0  3724    30411      149      14       3        0             0 crond
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.514018] [ 3738]     0  3738     4797       42      13       3        0             0 atd
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.518902] [ 3773]     0  3773     1090       24       8       3        0             0 mingetty
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.524491] [ 3775]     0  3775     1627       31       9       3        0             0 agetty
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.529721] [ 3778]     0  3778     1090       24       8       3        0             0 mingetty
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.535029] [ 3781]     0  3781     1090       24       8       3        0             0 mingetty
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.540245] [ 3783]     0  3783     1090       24       8       3        0             0 mingetty
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.545404] [ 3785]     0  3785     1090       24       8       3        0             0 mingetty
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.550610] [ 3787]     0  3787     1090       25       8       3        0             0 mingetty
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.556012] [ 4948]   500  4948    28285       60      12       3        0             0 start_server.sh
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.561798] [ 4973]   500  4973 4295425981     2435      71       5        0             0 java
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.566936] Out of memory: Kill process 4973 (java) score 0 or sacrifice child
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.571217] Killed process 4973 (java) total-vm:17181703924kB, anon-rss:9740kB, file-rss:0kB, shmem-rss:0kB
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.578364] oom_reaper: reaped process 4973 (java), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB

更新: 看起来 17 TB 虚拟内存(在top应用程序运行期间也可见)并不是什么问题。

我们设置了一个简单的 Spring Boot hello world 应用程序,除了启用 ZGC 之外,其余设置均采用默认设置,结果发生了同样的事情。看起来 ZGC 会分配 4 TB 的地址空间,而不管堆大小如何,并且还会多次映射相同的物理地址,因此这显然是正常的。我找不到任何人讨论它,这很令人惊讶。

当我们尝试关闭应用程序时,OOM-Killer 似乎参与其中。考虑到我们无论如何都会尝试关闭它,所以我并不特别担心。

再次感谢大家的帮助。

答案1

内存不足。

12月18日 23:24:59 ip-10-0-3-36 内核:[775.566936]内存不足:杀死进程 4973 (java) 得分 0 或牺牲子进程

来自同一个日志(ps);

[775.561798] [4973] 500 4973 4295425981 2435 71 5 0 0 Java

4295425.981 大约为 4TB。而 total-vm:17181703924kB 这一行显示大约为 17TB。

您可以调试您的内存分配例程吗?对我来说,您的应用程序在某处出现了错误循环,必须使用所有可用的资源以及可用的交换资源。

答案2

Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.214705]  shmem_fallocate+0x32d/0x440
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.217182]  vfs_fallocate+0x13f/0x260
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.219525]  SyS_fallocate+0x43/0x80
Dec 18 23:24:59 ip-10-0-3-36 kernel: [  775.221657]  do_syscall_64+0x67/0x100

您的应用程序进程正在尝试调用fallocateshmem 文件系统。来自快速谷歌搜索看起来 ZGC 使用 fallocate 从 shm 文件系统中获取初始堆内存,然后继续使用 fallocate 扩展堆。这种 fallocate 系统调用的使用相当不寻常,因此要么这是 ZGC 错误(正如您已经怀疑的那样),要么是其他东西泄漏了大量内存,导致堆扩展失败。

我建议你配置 ZGC 以避免额外的运行时分配(设置XmsXmx为相同的值)。如果内存泄漏是由于不相关的原因而发生的,这可能无法解决你的问题,但至少你有更好的机会找到真正的罪魁祸首。

请注意,您的整体设置有些危险——ZGC 显然喜欢拥有大量连续内存,但如果您在 240G RAM 的机器上有 190G 堆,则可能没有足够大的连续区域可供选择fallocate。在这种情况下,ZGC 将回退到通过进一步调用拾取小内存区域fallocate(请参阅链接的错误报告的描述),问题将再次变得模糊... 在 JVM 中启用大页面支持(正常大页面, 不是透明大页面!) 并在启动期间预分配大页面(使用内核参数)——无论如何,对于您的堆大小,使用大页面都是明智的。

答案3

所以,总而言之,这个问题被证明是一些本机内存泄漏(即非堆)。我们修补了操作系统,它从大量(几天内就会死掉)变成了几乎为零(几个月内就会死掉)。操作系统补丁说明修复了一些内存管理方面的错误,但对我来说,这有点太低级了,无法理解细节。

仍有轻微的本机内存泄漏,但已不再紧急。我们将继续监控。如果有任何补丁进一步解决,我将更新此答案。

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