大量的SIGSEGV雖然strace'ing Java過程

Question

有趣的東西發生時，我調試CI服務器上的單元測試之一（實際上maven構建）。我使用strace -ff -e trace=network -p [pid]連接到java進程以跟蹤構建過程的網絡活動。這就是我所看到的：

Process 26324 attached 
Process 26325 attached (waiting for parent) 
Process 26325 resumed (parent 26312 ready) 
Process 26325 detached 
Process 26324 detached 
Process 26320 detached 
Process 26317 detached 
Process 26308 resumed 
[pid 26308] --- SIGCHLD (Child exited) @ 0 (0) --- 
Process 26307 resumed 
Process 26308 detached 
[pid 26310] --- SIGCHLD (Child exited) @ 0 (0) --- 
Process 26310 detached 
[pid 25551] --- SIGSEGV (Segmentation fault) @ 0 (0) --- 
Process 26309 detached 
Process 26307 detached 
[pid 25717] --- SIGSEGV (Segmentation fault) @ 0 (0) --- 
[pid 25715] --- SIGSEGV (Segmentation fault) @ 0 (0) --- 
[pid 25713] --- SIGSEGV (Segmentation fault) @ 0 (0) --- 
[pid 25551] socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 163 
[pid 25551] setsockopt(163, SOL_SOCKET, SO_BROADCAST, [1], 4) = 0 
[pid 25551] bind(163, {sa_family=AF_INET, sin_port=htons(6590), sin_addr=inet_addr("0.0.0.0")}, 16) = 0 
Process 26471 attached (waiting for parent) 
Process 26471 resumed (parent 25551 ready) 
[pid 25551] --- SIGSEGV (Segmentation fault) @ 0 (0) --- 
[pid 25551] --- SIGSEGV (Segmentation fault) @ 0 (0) --- 
[pid 26471] recvfrom(163, <unfinished ...> 
[pid 25551] socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 164 
[pid 25551] setsockopt(164, SOL_SOCKET, SO_BROADCAST, [1], 4) = 0 
[pid 25551] bind(164, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("0.0.0.0")}, 16) = 0 
[pid 25551] getsockname(164, {sa_family=AF_INET, sin_port=htons(45728), sin_addr=inet_addr("0.0.0.0")},[16]) = 0 
[pid 25551] --- SIGSEGV (Segmentation fault) @ 0 (0) --- 
[pid 26471] <... recvfrom resumed> 0x8e80618, 65536, 0, 0x6ef6aea0, 0x6ef6ae9c) = ? ERESTARTSYS (To be restarted) 
[pid 26471] --- SIGRT_29 (Real-time signal 27) @ 0 (0) --- 
Process 26471 detached 
Process 26472 attached (waiting for parent) 
Process 26472 resumed (parent 25551 ready) 
Process 26473 attached (waiting for parent) 
Process 26473 resumed (parent 25551 ready) 

因此，有我們有一些網絡活動（這是什麼，我其實搜索），很多SIGSEGV信號。

構建完成正確（只是一個破碎的測試）。情況一次又一次地可確定和再現。這是什麼意思？

Answer 1

由於這是java，這意味着您的JVM正在使用SIGSEGVs來實現某些功能。常見的用途包括

• 空指針引用 - ，JVM可以捕獲SIGSEGVs地址0，並把它們轉化成NullPointerExceptions的

• 垃圾收集寫屏障 - 很少更改的頁面都標記爲只讀和SEGVs抓寫入他們。這樣垃圾收集器就不必重新掃描所有的內存。