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| 1 # Copyright 2014 The Chromium Authors. All rights reserved. | |
| 2 # Use of this source code is governed by a BSD-style license that can be | |
| 3 # found in the LICENSE file. | |
| 4 | |
| 5 import collections | |
| 6 import datetime | |
| 7 import logging | |
| 8 import multiprocessing | |
| 9 import os | |
| 10 import posixpath | |
| 11 import Queue | |
| 12 import re | |
| 13 import subprocess | |
| 14 import sys | |
| 15 import threading | |
| 16 import time | |
| 17 | |
| 18 | |
| 19 # addr2line builds a possibly infinite memory cache that can exhaust | |
| 20 # the computer's memory if allowed to grow for too long. This constant | |
| 21 # controls how many lookups we do before restarting the process. 4000 | |
| 22 # gives near peak performance without extreme memory usage. | |
| 23 ADDR2LINE_RECYCLE_LIMIT = 4000 | |
| 24 | |
| 25 | |
| 26 class ELFSymbolizer(object): | |
| 27 """An uber-fast (multiprocessing, pipelined and asynchronous) ELF symbolizer. | |
| 28 | |
| 29 This class is a frontend for addr2line (part of GNU binutils), designed to | |
| 30 symbolize batches of large numbers of symbols for a given ELF file. It | |
| 31 supports sharding symbolization against many addr2line instances and | |
| 32 pipelining of multiple requests per each instance (in order to hide addr2line | |
| 33 internals and OS pipe latencies). | |
| 34 | |
| 35 The interface exhibited by this class is a very simple asynchronous interface, | |
| 36 which is based on the following three methods: | |
| 37 - SymbolizeAsync(): used to request (enqueue) resolution of a given address. | |
| 38 - The |callback| method: used to communicated back the symbol information. | |
| 39 - Join(): called to conclude the batch to gather the last outstanding results. | |
| 40 In essence, before the Join method returns, this class will have issued as | |
| 41 many callbacks as the number of SymbolizeAsync() calls. In this regard, note | |
| 42 that due to multiprocess sharding, callbacks can be delivered out of order. | |
| 43 | |
| 44 Some background about addr2line: | |
| 45 - it is invoked passing the elf path in the cmdline, piping the addresses in | |
| 46 its stdin and getting results on its stdout. | |
| 47 - it has pretty large response times for the first requests, but it | |
| 48 works very well in streaming mode once it has been warmed up. | |
| 49 - it doesn't scale by itself (on more cores). However, spawning multiple | |
| 50 instances at the same time on the same file is pretty efficient as they | |
| 51 keep hitting the pagecache and become mostly CPU bound. | |
| 52 - it might hang or crash, mostly for OOM. This class deals with both of these | |
| 53 problems. | |
| 54 | |
| 55 Despite the "scary" imports and the multi* words above, (almost) no multi- | |
| 56 threading/processing is involved from the python viewpoint. Concurrency | |
| 57 here is achieved by spawning several addr2line subprocesses and handling their | |
| 58 output pipes asynchronously. Therefore, all the code here (with the exception | |
| 59 of the Queue instance in Addr2Line) should be free from mind-blowing | |
| 60 thread-safety concerns. | |
| 61 | |
| 62 The multiprocess sharding works as follows: | |
| 63 The symbolizer tries to use the lowest number of addr2line instances as | |
| 64 possible (with respect of |max_concurrent_jobs|) and enqueue all the requests | |
| 65 in a single addr2line instance. For few symbols (i.e. dozens) sharding isn't | |
| 66 worth the startup cost. | |
| 67 The multiprocess logic kicks in as soon as the queues for the existing | |
| 68 instances grow. Specifically, once all the existing instances reach the | |
| 69 |max_queue_size| bound, a new addr2line instance is kicked in. | |
| 70 In the case of a very eager producer (i.e. all |max_concurrent_jobs| instances | |
| 71 have a backlog of |max_queue_size|), back-pressure is applied on the caller by | |
| 72 blocking the SymbolizeAsync method. | |
| 73 | |
| 74 This module has been deliberately designed to be dependency free (w.r.t. of | |
| 75 other modules in this project), to allow easy reuse in external projects. | |
| 76 """ | |
| 77 | |
| 78 def __init__(self, elf_file_path, addr2line_path, callback, inlines=False, | |
| 79 max_concurrent_jobs=None, addr2line_timeout=30, max_queue_size=50, | |
| 80 source_root_path=None, strip_base_path=None): | |
| 81 """Args: | |
| 82 elf_file_path: path of the elf file to be symbolized. | |
| 83 addr2line_path: path of the toolchain's addr2line binary. | |
| 84 callback: a callback which will be invoked for each resolved symbol with | |
| 85 the two args (sym_info, callback_arg). The former is an instance of | |
| 86 |ELFSymbolInfo| and contains the symbol information. The latter is an | |
| 87 embedder-provided argument which is passed to SymbolizeAsync(). | |
| 88 inlines: when True, the ELFSymbolInfo will contain also the details about | |
| 89 the outer inlining functions. When False, only the innermost function | |
| 90 will be provided. | |
| 91 max_concurrent_jobs: Max number of addr2line instances spawned. | |
| 92 Parallelize responsibly, addr2line is a memory and I/O monster. | |
| 93 max_queue_size: Max number of outstanding requests per addr2line instance. | |
| 94 addr2line_timeout: Max time (in seconds) to wait for a addr2line response. | |
| 95 After the timeout, the instance will be considered hung and respawned. | |
| 96 source_root_path: In some toolchains only the name of the source file is | |
| 97 is output, without any path information; disambiguation searches | |
| 98 through the source directory specified by |source_root_path| argument | |
| 99 for files whose name matches, adding the full path information to the | |
| 100 output. For example, if the toolchain outputs "unicode.cc" and there | |
| 101 is a file called "unicode.cc" located under |source_root_path|/foo, | |
| 102 the tool will replace "unicode.cc" with | |
| 103 "|source_root_path|/foo/unicode.cc". If there are multiple files with | |
| 104 the same name, disambiguation will fail because the tool cannot | |
| 105 determine which of the files was the source of the symbol. | |
| 106 strip_base_path: Rebases the symbols source paths onto |source_root_path| | |
| 107 (i.e replace |strip_base_path| with |source_root_path). | |
| 108 """ | |
| 109 assert(os.path.isfile(addr2line_path)), 'Cannot find ' + addr2line_path | |
| 110 self.elf_file_path = elf_file_path | |
| 111 self.addr2line_path = addr2line_path | |
| 112 self.callback = callback | |
| 113 self.inlines = inlines | |
| 114 self.max_concurrent_jobs = (max_concurrent_jobs or | |
| 115 min(multiprocessing.cpu_count(), 4)) | |
| 116 self.max_queue_size = max_queue_size | |
| 117 self.addr2line_timeout = addr2line_timeout | |
| 118 self.requests_counter = 0 # For generating monotonic request IDs. | |
| 119 self._a2l_instances = [] # Up to |max_concurrent_jobs| _Addr2Line inst. | |
| 120 | |
| 121 # If necessary, create disambiguation lookup table | |
| 122 self.disambiguate = source_root_path is not None | |
| 123 self.disambiguation_table = {} | |
| 124 self.strip_base_path = strip_base_path | |
| 125 if(self.disambiguate): | |
| 126 self.source_root_path = os.path.abspath(source_root_path) | |
| 127 self._CreateDisambiguationTable() | |
| 128 | |
| 129 # Create one addr2line instance. More instances will be created on demand | |
| 130 # (up to |max_concurrent_jobs|) depending on the rate of the requests. | |
| 131 self._CreateNewA2LInstance() | |
| 132 | |
| 133 def SymbolizeAsync(self, addr, callback_arg=None): | |
| 134 """Requests symbolization of a given address. | |
| 135 | |
| 136 This method is not guaranteed to return immediately. It generally does, but | |
| 137 in some scenarios (e.g. all addr2line instances have full queues) it can | |
| 138 block to create back-pressure. | |
| 139 | |
| 140 Args: | |
| 141 addr: address to symbolize. | |
| 142 callback_arg: optional argument which will be passed to the |callback|.""" | |
| 143 assert(isinstance(addr, int)) | |
| 144 | |
| 145 # Process all the symbols that have been resolved in the meanwhile. | |
| 146 # Essentially, this drains all the addr2line(s) out queues. | |
| 147 for a2l_to_purge in self._a2l_instances: | |
| 148 a2l_to_purge.ProcessAllResolvedSymbolsInQueue() | |
| 149 a2l_to_purge.RecycleIfNecessary() | |
| 150 | |
| 151 # Find the best instance according to this logic: | |
| 152 # 1. Find an existing instance with the shortest queue. | |
| 153 # 2. If all of instances' queues are full, but there is room in the pool, | |
| 154 # (i.e. < |max_concurrent_jobs|) create a new instance. | |
| 155 # 3. If there were already |max_concurrent_jobs| instances and all of them | |
| 156 # had full queues, make back-pressure. | |
| 157 | |
| 158 # 1. | |
| 159 def _SortByQueueSizeAndReqID(a2l): | |
| 160 return (a2l.queue_size, a2l.first_request_id) | |
| 161 a2l = min(self._a2l_instances, key=_SortByQueueSizeAndReqID) | |
| 162 | |
| 163 # 2. | |
| 164 if (a2l.queue_size >= self.max_queue_size and | |
| 165 len(self._a2l_instances) < self.max_concurrent_jobs): | |
| 166 a2l = self._CreateNewA2LInstance() | |
| 167 | |
| 168 # 3. | |
| 169 if a2l.queue_size >= self.max_queue_size: | |
| 170 a2l.WaitForNextSymbolInQueue() | |
| 171 | |
| 172 a2l.EnqueueRequest(addr, callback_arg) | |
| 173 | |
| 174 def Join(self): | |
| 175 """Waits for all the outstanding requests to complete and terminates.""" | |
| 176 for a2l in self._a2l_instances: | |
| 177 a2l.WaitForIdle() | |
| 178 a2l.Terminate() | |
| 179 | |
| 180 def _CreateNewA2LInstance(self): | |
| 181 assert(len(self._a2l_instances) < self.max_concurrent_jobs) | |
| 182 a2l = ELFSymbolizer.Addr2Line(self) | |
| 183 self._a2l_instances.append(a2l) | |
| 184 return a2l | |
| 185 | |
| 186 def _CreateDisambiguationTable(self): | |
| 187 """ Non-unique file names will result in None entries""" | |
| 188 start_time = time.time() | |
| 189 logging.info('Collecting information about available source files...') | |
| 190 self.disambiguation_table = {} | |
| 191 | |
| 192 for root, _, filenames in os.walk(self.source_root_path): | |
| 193 for f in filenames: | |
| 194 self.disambiguation_table[f] = os.path.join(root, f) if (f not in | |
| 195 self.disambiguation_table) else None | |
| 196 logging.info('Finished collecting information about ' | |
| 197 'possible files (took %.1f s).', | |
| 198 (time.time() - start_time)) | |
| 199 | |
| 200 | |
| 201 class Addr2Line(object): | |
| 202 """A python wrapper around an addr2line instance. | |
| 203 | |
| 204 The communication with the addr2line process looks as follows: | |
| 205 [STDIN] [STDOUT] (from addr2line's viewpoint) | |
| 206 > f001111 | |
| 207 > f002222 | |
| 208 < Symbol::Name(foo, bar) for f001111 | |
| 209 < /path/to/source/file.c:line_number | |
| 210 > f003333 | |
| 211 < Symbol::Name2() for f002222 | |
| 212 < /path/to/source/file.c:line_number | |
| 213 < Symbol::Name3() for f003333 | |
| 214 < /path/to/source/file.c:line_number | |
| 215 """ | |
| 216 | |
| 217 SYM_ADDR_RE = re.compile(r'([^:]+):(\?|\d+).*') | |
| 218 | |
| 219 def __init__(self, symbolizer): | |
| 220 self._symbolizer = symbolizer | |
| 221 self._lib_file_name = posixpath.basename(symbolizer.elf_file_path) | |
| 222 | |
| 223 # The request queue (i.e. addresses pushed to addr2line's stdin and not | |
| 224 # yet retrieved on stdout) | |
| 225 self._request_queue = collections.deque() | |
| 226 | |
| 227 # This is essentially len(self._request_queue). It has been optimized to a | |
| 228 # separate field because turned out to be a perf hot-spot. | |
| 229 self.queue_size = 0 | |
| 230 | |
| 231 # Keep track of the number of symbols a process has processed to | |
| 232 # avoid a single process growing too big and using all the memory. | |
| 233 self._processed_symbols_count = 0 | |
| 234 | |
| 235 # Objects required to handle the addr2line subprocess. | |
| 236 self._proc = None # Subprocess.Popen(...) instance. | |
| 237 self._thread = None # Threading.thread instance. | |
| 238 self._out_queue = None # Queue.Queue instance (for buffering a2l stdout). | |
| 239 self._RestartAddr2LineProcess() | |
| 240 | |
| 241 def EnqueueRequest(self, addr, callback_arg): | |
| 242 """Pushes an address to addr2line's stdin (and keeps track of it).""" | |
| 243 self._symbolizer.requests_counter += 1 # For global "age" of requests. | |
| 244 req_idx = self._symbolizer.requests_counter | |
| 245 self._request_queue.append((addr, callback_arg, req_idx)) | |
| 246 self.queue_size += 1 | |
| 247 self._WriteToA2lStdin(addr) | |
| 248 | |
| 249 def WaitForIdle(self): | |
| 250 """Waits until all the pending requests have been symbolized.""" | |
| 251 while self.queue_size > 0: | |
| 252 self.WaitForNextSymbolInQueue() | |
| 253 | |
| 254 def WaitForNextSymbolInQueue(self): | |
| 255 """Waits for the next pending request to be symbolized.""" | |
| 256 if not self.queue_size: | |
| 257 return | |
| 258 | |
| 259 # This outer loop guards against a2l hanging (detecting stdout timeout). | |
| 260 while True: | |
| 261 start_time = datetime.datetime.now() | |
| 262 timeout = datetime.timedelta(seconds=self._symbolizer.addr2line_timeout) | |
| 263 | |
| 264 # The inner loop guards against a2l crashing (checking if it exited). | |
| 265 while (datetime.datetime.now() - start_time < timeout): | |
| 266 # poll() returns !None if the process exited. a2l should never exit. | |
| 267 if self._proc.poll(): | |
| 268 logging.warning('addr2line crashed, respawning (lib: %s).' % | |
| 269 self._lib_file_name) | |
| 270 self._RestartAddr2LineProcess() | |
| 271 # TODO(primiano): the best thing to do in this case would be | |
| 272 # shrinking the pool size as, very likely, addr2line is crashed | |
| 273 # due to low memory (and the respawned one will die again soon). | |
| 274 | |
| 275 try: | |
| 276 lines = self._out_queue.get(block=True, timeout=0.25) | |
| 277 except Queue.Empty: | |
| 278 # On timeout (1/4 s.) repeat the inner loop and check if either the | |
| 279 # addr2line process did crash or we waited its output for too long. | |
| 280 continue | |
| 281 | |
| 282 # In nominal conditions, we get straight to this point. | |
| 283 self._ProcessSymbolOutput(lines) | |
| 284 return | |
| 285 | |
| 286 # If this point is reached, we waited more than |addr2line_timeout|. | |
| 287 logging.warning('Hung addr2line process, respawning (lib: %s).' % | |
| 288 self._lib_file_name) | |
| 289 self._RestartAddr2LineProcess() | |
| 290 | |
| 291 def ProcessAllResolvedSymbolsInQueue(self): | |
| 292 """Consumes all the addr2line output lines produced (without blocking).""" | |
| 293 if not self.queue_size: | |
| 294 return | |
| 295 while True: | |
| 296 try: | |
| 297 lines = self._out_queue.get_nowait() | |
| 298 except Queue.Empty: | |
| 299 break | |
| 300 self._ProcessSymbolOutput(lines) | |
| 301 | |
| 302 def RecycleIfNecessary(self): | |
| 303 """Restarts the process if it has been used for too long. | |
| 304 | |
| 305 A long running addr2line process will consume excessive amounts | |
| 306 of memory without any gain in performance.""" | |
| 307 if self._processed_symbols_count >= ADDR2LINE_RECYCLE_LIMIT: | |
| 308 self._RestartAddr2LineProcess() | |
| 309 | |
| 310 | |
| 311 def Terminate(self): | |
| 312 """Kills the underlying addr2line process. | |
| 313 | |
| 314 The poller |_thread| will terminate as well due to the broken pipe.""" | |
| 315 try: | |
| 316 self._proc.kill() | |
| 317 self._proc.communicate() # Essentially wait() without risking deadlock. | |
| 318 except Exception: # An exception while terminating? How interesting. | |
| 319 pass | |
| 320 self._proc = None | |
| 321 | |
| 322 def _WriteToA2lStdin(self, addr): | |
| 323 self._proc.stdin.write('%s\n' % hex(addr)) | |
| 324 if self._symbolizer.inlines: | |
| 325 # In the case of inlines we output an extra blank line, which causes | |
| 326 # addr2line to emit a (??,??:0) tuple that we use as a boundary marker. | |
| 327 self._proc.stdin.write('\n') | |
| 328 self._proc.stdin.flush() | |
| 329 | |
| 330 def _ProcessSymbolOutput(self, lines): | |
| 331 """Parses an addr2line symbol output and triggers the client callback.""" | |
| 332 (_, callback_arg, _) = self._request_queue.popleft() | |
| 333 self.queue_size -= 1 | |
| 334 | |
| 335 innermost_sym_info = None | |
| 336 sym_info = None | |
| 337 for (line1, line2) in lines: | |
| 338 prev_sym_info = sym_info | |
| 339 name = line1 if not line1.startswith('?') else None | |
| 340 source_path = None | |
| 341 source_line = None | |
| 342 m = ELFSymbolizer.Addr2Line.SYM_ADDR_RE.match(line2) | |
| 343 if m: | |
| 344 if not m.group(1).startswith('?'): | |
| 345 source_path = m.group(1) | |
| 346 if not m.group(2).startswith('?'): | |
| 347 source_line = int(m.group(2)) | |
| 348 else: | |
| 349 logging.warning('Got invalid symbol path from addr2line: %s' % line2) | |
| 350 | |
| 351 # In case disambiguation is on, and needed | |
| 352 was_ambiguous = False | |
| 353 disambiguated = False | |
| 354 if self._symbolizer.disambiguate: | |
| 355 if source_path and not posixpath.isabs(source_path): | |
| 356 path = self._symbolizer.disambiguation_table.get(source_path) | |
| 357 was_ambiguous = True | |
| 358 disambiguated = path is not None | |
| 359 source_path = path if disambiguated else source_path | |
| 360 | |
| 361 # Use absolute paths (so that paths are consistent, as disambiguation | |
| 362 # uses absolute paths) | |
| 363 if source_path and not was_ambiguous: | |
| 364 source_path = os.path.abspath(source_path) | |
| 365 | |
| 366 if source_path and self._symbolizer.strip_base_path: | |
| 367 # Strip the base path | |
| 368 source_path = re.sub('^' + self._symbolizer.strip_base_path, | |
| 369 self._symbolizer.source_root_path or '', source_path) | |
| 370 | |
| 371 sym_info = ELFSymbolInfo(name, source_path, source_line, was_ambiguous, | |
| 372 disambiguated) | |
| 373 if prev_sym_info: | |
| 374 prev_sym_info.inlined_by = sym_info | |
| 375 if not innermost_sym_info: | |
| 376 innermost_sym_info = sym_info | |
| 377 | |
| 378 self._processed_symbols_count += 1 | |
| 379 self._symbolizer.callback(innermost_sym_info, callback_arg) | |
| 380 | |
| 381 def _RestartAddr2LineProcess(self): | |
| 382 if self._proc: | |
| 383 self.Terminate() | |
| 384 | |
| 385 # The only reason of existence of this Queue (and the corresponding | |
| 386 # Thread below) is the lack of a subprocess.stdout.poll_avail_lines(). | |
| 387 # Essentially this is a pipe able to extract a couple of lines atomically. | |
| 388 self._out_queue = Queue.Queue() | |
| 389 | |
| 390 # Start the underlying addr2line process in line buffered mode. | |
| 391 | |
| 392 cmd = [self._symbolizer.addr2line_path, '--functions', '--demangle', | |
| 393 '--exe=' + self._symbolizer.elf_file_path] | |
| 394 if self._symbolizer.inlines: | |
| 395 cmd += ['--inlines'] | |
| 396 self._proc = subprocess.Popen(cmd, bufsize=1, stdout=subprocess.PIPE, | |
| 397 stdin=subprocess.PIPE, stderr=sys.stderr, close_fds=True) | |
| 398 | |
| 399 # Start the poller thread, which simply moves atomically the lines read | |
| 400 # from the addr2line's stdout to the |_out_queue|. | |
| 401 self._thread = threading.Thread( | |
| 402 target=ELFSymbolizer.Addr2Line.StdoutReaderThread, | |
| 403 args=(self._proc.stdout, self._out_queue, self._symbolizer.inlines)) | |
| 404 self._thread.daemon = True # Don't prevent early process exit. | |
| 405 self._thread.start() | |
| 406 | |
| 407 self._processed_symbols_count = 0 | |
| 408 | |
| 409 # Replay the pending requests on the new process (only for the case | |
| 410 # of a hung addr2line timing out during the game). | |
| 411 for (addr, _, _) in self._request_queue: | |
| 412 self._WriteToA2lStdin(addr) | |
| 413 | |
| 414 @staticmethod | |
| 415 def StdoutReaderThread(process_pipe, queue, inlines): | |
| 416 """The poller thread fn, which moves the addr2line stdout to the |queue|. | |
| 417 | |
| 418 This is the only piece of code not running on the main thread. It merely | |
| 419 writes to a Queue, which is thread-safe. In the case of inlines, it | |
| 420 detects the ??,??:0 marker and sends the lines atomically, such that the | |
| 421 main thread always receives all the lines corresponding to one symbol in | |
| 422 one shot.""" | |
| 423 try: | |
| 424 lines_for_one_symbol = [] | |
| 425 while True: | |
| 426 line1 = process_pipe.readline().rstrip('\r\n') | |
| 427 line2 = process_pipe.readline().rstrip('\r\n') | |
| 428 if not line1 or not line2: | |
| 429 break | |
| 430 inline_has_more_lines = inlines and (len(lines_for_one_symbol) == 0 or | |
| 431 (line1 != '??' and line2 != '??:0')) | |
| 432 if not inlines or inline_has_more_lines: | |
| 433 lines_for_one_symbol += [(line1, line2)] | |
| 434 if inline_has_more_lines: | |
| 435 continue | |
| 436 queue.put(lines_for_one_symbol) | |
| 437 lines_for_one_symbol = [] | |
| 438 process_pipe.close() | |
| 439 | |
| 440 # Every addr2line processes will die at some point, please die silently. | |
| 441 except (IOError, OSError): | |
| 442 pass | |
| 443 | |
| 444 @property | |
| 445 def first_request_id(self): | |
| 446 """Returns the request_id of the oldest pending request in the queue.""" | |
| 447 return self._request_queue[0][2] if self._request_queue else 0 | |
| 448 | |
| 449 | |
| 450 class ELFSymbolInfo(object): | |
| 451 """The result of the symbolization passed as first arg. of each callback.""" | |
| 452 | |
| 453 def __init__(self, name, source_path, source_line, was_ambiguous=False, | |
| 454 disambiguated=False): | |
| 455 """All the fields here can be None (if addr2line replies with '??').""" | |
| 456 self.name = name | |
| 457 self.source_path = source_path | |
| 458 self.source_line = source_line | |
| 459 # In the case of |inlines|=True, the |inlined_by| points to the outer | |
| 460 # function inlining the current one (and so on, to form a chain). | |
| 461 self.inlined_by = None | |
| 462 self.disambiguated = disambiguated | |
| 463 self.was_ambiguous = was_ambiguous | |
| 464 | |
| 465 def __str__(self): | |
| 466 return '%s [%s:%d]' % ( | |
| 467 self.name or '??', self.source_path or '??', self.source_line or 0) | |
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Chromium Code Reviews
Issue 2392643003:
Removes files from //build that we don't need (Closed)
