1 /*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 /*
18 * This is a thread that catches signals and does something useful. For
19 * example, when a SIGQUIT (Ctrl-\) arrives, suspend the VM and dump the
20 * status of all threads.
21 */
22 #include "Dalvik.h"
23
24 #include <stdlib.h>
25 #include <unistd.h>
26 #include <signal.h>
27 #include <pthread.h>
28 #include <sys/file.h>
29 #include <sys/time.h>
30 #include <fcntl.h>
31 #include <errno.h>
32
33 #include <cutils/open_memstream.h>
34
35 static void* signalCatcherThreadStart(void* arg);
36
37 /*
38 * Crank up the signal catcher thread.
39 *
40 * Returns immediately.
41 */
dvmSignalCatcherStartup(void)42 bool dvmSignalCatcherStartup(void)
43 {
44 gDvm.haltSignalCatcher = false;
45
46 if (!dvmCreateInternalThread(&gDvm.signalCatcherHandle,
47 "Signal Catcher", signalCatcherThreadStart, NULL))
48 return false;
49
50 return true;
51 }
52
53 /*
54 * Shut down the signal catcher thread if it was started.
55 *
56 * Since we know the thread is just sitting around waiting for signals
57 * to arrive, send it one.
58 */
dvmSignalCatcherShutdown(void)59 void dvmSignalCatcherShutdown(void)
60 {
61 gDvm.haltSignalCatcher = true;
62 if (gDvm.signalCatcherHandle == 0) // not started yet
63 return;
64
65 pthread_kill(gDvm.signalCatcherHandle, SIGQUIT);
66
67 pthread_join(gDvm.signalCatcherHandle, NULL);
68 LOGV("signal catcher has shut down\n");
69 }
70
71
72 /*
73 * Print the name of the current process, if we can get it.
74 */
printProcessName(const DebugOutputTarget * target)75 static void printProcessName(const DebugOutputTarget* target)
76 {
77 int fd = -1;
78
79 fd = open("/proc/self/cmdline", O_RDONLY, 0);
80 if (fd < 0)
81 goto bail;
82
83 char tmpBuf[256];
84 ssize_t actual;
85
86 actual = read(fd, tmpBuf, sizeof(tmpBuf)-1);
87 if (actual <= 0)
88 goto bail;
89
90 tmpBuf[actual] = '\0';
91 dvmPrintDebugMessage(target, "Cmd line: %s\n", tmpBuf);
92
93 bail:
94 if (fd >= 0)
95 close(fd);
96 }
97
98 /*
99 * Dump the stack traces for all threads to the supplied file, putting
100 * a timestamp header on it.
101 */
logThreadStacks(FILE * fp)102 static void logThreadStacks(FILE* fp)
103 {
104 DebugOutputTarget target;
105
106 dvmCreateFileOutputTarget(&target, fp);
107
108 pid_t pid = getpid();
109 time_t now = time(NULL);
110 struct tm* ptm;
111 #ifdef HAVE_LOCALTIME_R
112 struct tm tmbuf;
113 ptm = localtime_r(&now, &tmbuf);
114 #else
115 ptm = localtime(&now);
116 #endif
117 dvmPrintDebugMessage(&target,
118 "\n\n----- pid %d at %04d-%02d-%02d %02d:%02d:%02d -----\n",
119 pid, ptm->tm_year + 1900, ptm->tm_mon+1, ptm->tm_mday,
120 ptm->tm_hour, ptm->tm_min, ptm->tm_sec);
121 printProcessName(&target);
122 dvmPrintDebugMessage(&target, "\n");
123 dvmDumpAllThreadsEx(&target, true);
124 fprintf(fp, "----- end %d -----\n", pid);
125 }
126
127
128 /*
129 * Respond to a SIGQUIT by dumping the thread stacks. Optionally dump
130 * a few other things while we're at it.
131 *
132 * Thread stacks can either go to the log or to a file designated for holding
133 * ANR traces. If we're writing to a file, we want to do it in one shot,
134 * so we can use a single O_APPEND write instead of contending for exclusive
135 * access with flock(). There may be an advantage in resuming the VM
136 * before doing the file write, so we don't stall the VM if disk I/O is
137 * bottlenecked.
138 *
139 * If JIT tuning is compiled in, dump compiler stats as well.
140 */
handleSigQuit(void)141 static void handleSigQuit(void)
142 {
143 char* traceBuf = NULL;
144 size_t traceLen;
145
146 dvmSuspendAllThreads(SUSPEND_FOR_STACK_DUMP);
147
148 dvmDumpLoaderStats("sig");
149
150 if (gDvm.stackTraceFile == NULL) {
151 /* just dump to log */
152 DebugOutputTarget target;
153 dvmCreateLogOutputTarget(&target, ANDROID_LOG_INFO, LOG_TAG);
154 dvmDumpAllThreadsEx(&target, true);
155 } else {
156 /* write to memory buffer */
157 FILE* memfp = open_memstream(&traceBuf, &traceLen);
158 if (memfp == NULL) {
159 LOGE("Unable to create memstream for stack traces\n");
160 traceBuf = NULL; /* make sure it didn't touch this */
161 /* continue on */
162 } else {
163 logThreadStacks(memfp);
164 fclose(memfp);
165 }
166 }
167
168 #if defined(WITH_JIT) && defined(WITH_JIT_TUNING)
169 dvmCompilerDumpStats();
170 #endif
171
172 if (false) {
173 dvmLockMutex(&gDvm.jniGlobalRefLock);
174 dvmDumpReferenceTable(&gDvm.jniGlobalRefTable, "JNI global");
175 dvmUnlockMutex(&gDvm.jniGlobalRefLock);
176 }
177 if (false) dvmDumpTrackedAllocations(true);
178
179 dvmResumeAllThreads(SUSPEND_FOR_STACK_DUMP);
180
181 if (traceBuf != NULL) {
182 /*
183 * We don't know how long it will take to do the disk I/O, so put us
184 * into VMWAIT for the duration.
185 */
186 int oldStatus = dvmChangeStatus(dvmThreadSelf(), THREAD_VMWAIT);
187
188 /*
189 * Open the stack trace output file, creating it if necessary. It
190 * needs to be world-writable so other processes can write to it.
191 */
192 int fd = open(gDvm.stackTraceFile, O_WRONLY | O_APPEND | O_CREAT, 0666);
193 if (fd < 0) {
194 LOGE("Unable to open stack trace file '%s': %s\n",
195 gDvm.stackTraceFile, strerror(errno));
196 } else {
197 ssize_t actual = write(fd, traceBuf, traceLen);
198 if (actual != (ssize_t) traceLen) {
199 LOGE("Failed to write stack traces to %s (%d of %zd): %s\n",
200 gDvm.stackTraceFile, (int) actual, traceLen,
201 strerror(errno));
202 } else {
203 LOGI("Wrote stack traces to '%s'\n", gDvm.stackTraceFile);
204 }
205 close(fd);
206 }
207
208 free(traceBuf);
209 dvmChangeStatus(dvmThreadSelf(), oldStatus);
210 }
211 }
212
213 /*
214 * Respond to a SIGUSR1 by forcing a GC.
215 */
handleSigUsr1(void)216 static void handleSigUsr1(void)
217 {
218 LOGI("SIGUSR1 forcing GC (no HPROF)\n");
219 dvmCollectGarbage(false);
220 }
221
222 #if defined(WITH_JIT) && defined(WITH_JIT_TUNING)
223 /*
224 * Respond to a SIGUSR2 by dumping some JIT stats and possibly resetting
225 * the code cache.
226 */
handleSigUsr2(void)227 static void handleSigUsr2(void)
228 {
229 static int codeCacheResetCount = 0;
230 if ((--codeCacheResetCount & 7) == 0) {
231 gDvmJit.codeCacheFull = true;
232 } else {
233 dvmCompilerDumpStats();
234 /* Stress-test unchain all */
235 dvmJitUnchainAll();
236 LOGD("Send %d more signals to rest the code cache",
237 codeCacheResetCount & 7);
238 }
239 }
240 #endif
241
242 /*
243 * Sleep in sigwait() until a signal arrives.
244 */
signalCatcherThreadStart(void * arg)245 static void* signalCatcherThreadStart(void* arg)
246 {
247 Thread* self = dvmThreadSelf();
248 sigset_t mask;
249 int cc;
250
251 UNUSED_PARAMETER(arg);
252
253 LOGV("Signal catcher thread started (threadid=%d)\n", self->threadId);
254
255 /* set up mask with signals we want to handle */
256 sigemptyset(&mask);
257 sigaddset(&mask, SIGQUIT);
258 sigaddset(&mask, SIGUSR1);
259 #if defined(WITH_JIT) && defined(WITH_JIT_TUNING)
260 sigaddset(&mask, SIGUSR2);
261 #endif
262
263 while (true) {
264 int rcvd;
265
266 dvmChangeStatus(self, THREAD_VMWAIT);
267
268 /*
269 * Signals for sigwait() must be blocked but not ignored. We
270 * block signals like SIGQUIT for all threads, so the condition
271 * is met. When the signal hits, we wake up, without any signal
272 * handlers being invoked.
273 *
274 * When running under GDB we occasionally return from sigwait()
275 * with EINTR (e.g. when other threads exit).
276 */
277 loop:
278 cc = sigwait(&mask, &rcvd);
279 if (cc != 0) {
280 if (cc == EINTR) {
281 //LOGV("sigwait: EINTR\n");
282 goto loop;
283 }
284 assert(!"bad result from sigwait");
285 }
286
287 if (!gDvm.haltSignalCatcher) {
288 LOGI("threadid=%d: reacting to signal %d\n",
289 dvmThreadSelf()->threadId, rcvd);
290 }
291
292 /* set our status to RUNNING, self-suspending if GC in progress */
293 dvmChangeStatus(self, THREAD_RUNNING);
294
295 if (gDvm.haltSignalCatcher)
296 break;
297
298 switch (rcvd) {
299 case SIGQUIT:
300 handleSigQuit();
301 break;
302 case SIGUSR1:
303 handleSigUsr1();
304 break;
305 #if defined(WITH_JIT) && defined(WITH_JIT_TUNING)
306 case SIGUSR2:
307 handleSigUsr2();
308 break;
309 #endif
310 default:
311 LOGE("unexpected signal %d\n", rcvd);
312 break;
313 }
314 }
315
316 return NULL;
317 }
318