Linux
請幫忙解讀OOM-Killer
我們正在測試我們的 java 應用程序，它被 OOM Killer 殺死，日誌如下。
幾點：這是一個 java web 應用程序。它以 190G 堆執行。伺服器是一個總記憶體為 240G 的 EC2 實例。我們在 JDK 11 中嘗試了新的、實驗性的 ZGC。當時應用程序沒有負載，在類似 prod 的測試環境中執行。該應用程序確實有一些調度觸發的處理，並且可能是記憶體和 CPU 密集型的，但這些處理經常執行並且沒有失敗。
應用程式碼與我們在生產中的程式碼沒有顯著變化。我們也成功地對此進行了負載測試，包括沒有問題的 12 小時浸泡測試。
現在查看 OOM-Killer 日誌。完整的日誌如下，但我覺得很奇怪的一件事是這一行：
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虛擬機總大小約為 17 TB。這對我來說很奇怪，因為我們的應用程序甚至不會嘗試正常請求這個。我懷疑我們可能遇到了一些 ZGC 或 ZGC+我們的程式碼錯誤，但想確保我沒看錯。
我非常感謝任何幫助，完整的日誌供參考：
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： 看起來 17 TB 虛擬記憶體（
top在應用程序執行期間也可見）並不是真正的問題。我們設置了一個簡單的 Spring Boot hello world 應用程序，除了啟用 ZGC 之外的預設設置，同樣的事情發生了。看起來 ZGC 分配了 4 TB 的地址空間而不管堆大小，並且還會多次映射同一個物理地址，所以這顯然是正常的。我找不到任何人討論它，這令人驚訝。
當我們嘗試關閉應用程序時，OOM-Killer 似乎參與其中。鑑於我們無論如何都試圖關閉它，我並不特別擔心。
再次感謝大家的幫助。
記憶體不足。
12 月 18 日 23:24:59 ip-10-0-3-36 核心：
$$ 775.566936 $$ 記憶體不足：殺死程序 4973 (java) 得分 0 或犧牲孩子
來自同一日誌（ps）；
$$ 775.561798 $$ $$ 4973 $$ 500 4973 4295425981 2435 71 5 0 0 爪哇
4295425.981 大約是 4TB。並且行 total-vm:17181703924kB 顯示大約 17TB。
你能調試你的記憶體分配常式嗎？至於我，您的應用程序在某個地方出現了錯誤的循環，並且必須佔用所有可用的資源，並且交換也可用。
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您的應用程序程序正在嘗試
fallocate在 shmem 文件系統上呼叫。從快速Google搜尋來看，ZGC 似乎使用 fallocate 從 shm 文件系統中獲取初始堆記憶體，然後繼續使用 fallocate 來擴展堆。這種 fallocate 系統呼叫的使用是相當不尋常的，所以要麼這是一個 ZGC 錯誤（正如您已經懷疑的那樣），要麼是其他原因導致大量記憶體洩漏，從而導致堆擴展失敗。我建議，您配置 ZGC 以避免額外的執行時分配（設置
Xms和Xmx相同的值）。如果由於不相關的事情而發生記憶體洩漏，這可能無法解決您的問題，但至少您將有更好的機會找到真正的罪魁禍首。請注意，您的整體設置有些危險——ZGC 顯然喜歡擁有大量連續記憶體，但如果您在 240G RAM 機器上有 190G 堆，則可能沒有足夠大的連續區域可供使用
fallocate。在這種情況下，ZGC 將回退到通過進一步呼叫來拾取小記憶體區域fallocate（參見連結錯誤報告的描述），並且問題將再次變得模糊……在 JVM 中啟用大頁面支持（普通大頁面，而不是透明大頁面！）和在引導期間預分配大頁面（使用核心參數） - 無論如何，對於您的堆大小，建議使用大頁面。