Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 1 | # |
| 2 | # Module which supports allocation of memory from an mmap |
| 3 | # |
| 4 | # multiprocessing/heap.py |
| 5 | # |
R. David Murray | d382066 | 2010-12-14 01:41:07 +0000 | [diff] [blame] | 6 | # Copyright (c) 2006-2008, R Oudkerk |
Richard Oudkerk | 3e268aa | 2012-04-30 12:13:55 +0100 | [diff] [blame] | 7 | # Licensed to PSF under a Contributor Agreement. |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 8 | # |
| 9 | |
| 10 | import bisect |
| 11 | import mmap |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 12 | import os |
| 13 | import sys |
Richard Oudkerk | 84ed9a6 | 2013-08-14 15:35:41 +0100 | [diff] [blame] | 14 | import tempfile |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 15 | import threading |
Richard Oudkerk | 84ed9a6 | 2013-08-14 15:35:41 +0100 | [diff] [blame] | 16 | |
Richard Oudkerk | b1694cf | 2013-10-16 16:41:56 +0100 | [diff] [blame] | 17 | from . import context |
Richard Oudkerk | 84ed9a6 | 2013-08-14 15:35:41 +0100 | [diff] [blame] | 18 | from . import reduction |
| 19 | from . import util |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 20 | |
| 21 | __all__ = ['BufferWrapper'] |
| 22 | |
| 23 | # |
Eli Bendersky | 25f043b | 2013-07-30 06:12:49 -0700 | [diff] [blame] | 24 | # Inheritable class which wraps an mmap, and from which blocks can be allocated |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 25 | # |
| 26 | |
| 27 | if sys.platform == 'win32': |
| 28 | |
Antoine Pitrou | 23bba4c | 2012-04-18 20:51:15 +0200 | [diff] [blame] | 29 | import _winapi |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 30 | |
| 31 | class Arena(object): |
| 32 | |
Richard Oudkerk | 84ed9a6 | 2013-08-14 15:35:41 +0100 | [diff] [blame] | 33 | _rand = tempfile._RandomNameSequence() |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 34 | |
| 35 | def __init__(self, size): |
| 36 | self.size = size |
Richard Oudkerk | 84ed9a6 | 2013-08-14 15:35:41 +0100 | [diff] [blame] | 37 | for i in range(100): |
| 38 | name = 'pym-%d-%s' % (os.getpid(), next(self._rand)) |
| 39 | buf = mmap.mmap(-1, size, tagname=name) |
| 40 | if _winapi.GetLastError() == 0: |
| 41 | break |
| 42 | # We have reopened a preexisting mmap. |
| 43 | buf.close() |
| 44 | else: |
| 45 | raise FileExistsError('Cannot find name for new mmap') |
| 46 | self.name = name |
| 47 | self.buffer = buf |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 48 | self._state = (self.size, self.name) |
| 49 | |
| 50 | def __getstate__(self): |
Richard Oudkerk | b1694cf | 2013-10-16 16:41:56 +0100 | [diff] [blame] | 51 | context.assert_spawning(self) |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 52 | return self._state |
| 53 | |
| 54 | def __setstate__(self, state): |
| 55 | self.size, self.name = self._state = state |
| 56 | self.buffer = mmap.mmap(-1, self.size, tagname=self.name) |
Steve Dower | 438f4ab | 2014-12-17 06:35:49 -0800 | [diff] [blame] | 57 | # XXX Temporarily preventing buildbot failures while determining |
| 58 | # XXX the correct long-term fix. See issue 23060 |
| 59 | #assert _winapi.GetLastError() == _winapi.ERROR_ALREADY_EXISTS |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 60 | |
| 61 | else: |
| 62 | |
| 63 | class Arena(object): |
| 64 | |
Richard Oudkerk | 84ed9a6 | 2013-08-14 15:35:41 +0100 | [diff] [blame] | 65 | def __init__(self, size, fd=-1): |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 66 | self.size = size |
Richard Oudkerk | 84ed9a6 | 2013-08-14 15:35:41 +0100 | [diff] [blame] | 67 | self.fd = fd |
| 68 | if fd == -1: |
| 69 | self.fd, name = tempfile.mkstemp( |
| 70 | prefix='pym-%d-'%os.getpid(), dir=util.get_temp_dir()) |
| 71 | os.unlink(name) |
| 72 | util.Finalize(self, os.close, (self.fd,)) |
| 73 | with open(self.fd, 'wb', closefd=False) as f: |
Antoine Pitrou | d5aec7b | 2015-04-13 20:53:43 +0200 | [diff] [blame] | 74 | bs = 1024 * 1024 |
| 75 | if size >= bs: |
| 76 | zeros = b'\0' * bs |
| 77 | for _ in range(size // bs): |
| 78 | f.write(zeros) |
| 79 | del zeros |
| 80 | f.write(b'\0' * (size % bs)) |
| 81 | assert f.tell() == size |
Richard Oudkerk | 84ed9a6 | 2013-08-14 15:35:41 +0100 | [diff] [blame] | 82 | self.buffer = mmap.mmap(self.fd, self.size) |
| 83 | |
| 84 | def reduce_arena(a): |
| 85 | if a.fd == -1: |
| 86 | raise ValueError('Arena is unpicklable because ' |
| 87 | 'forking was enabled when it was created') |
| 88 | return rebuild_arena, (a.size, reduction.DupFd(a.fd)) |
| 89 | |
| 90 | def rebuild_arena(size, dupfd): |
| 91 | return Arena(size, dupfd.detach()) |
| 92 | |
| 93 | reduction.register(Arena, reduce_arena) |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 94 | |
| 95 | # |
| 96 | # Class allowing allocation of chunks of memory from arenas |
| 97 | # |
| 98 | |
| 99 | class Heap(object): |
| 100 | |
| 101 | _alignment = 8 |
| 102 | |
| 103 | def __init__(self, size=mmap.PAGESIZE): |
| 104 | self._lastpid = os.getpid() |
| 105 | self._lock = threading.Lock() |
| 106 | self._size = size |
| 107 | self._lengths = [] |
| 108 | self._len_to_seq = {} |
| 109 | self._start_to_block = {} |
| 110 | self._stop_to_block = {} |
| 111 | self._allocated_blocks = set() |
| 112 | self._arenas = [] |
Charles-François Natali | 778db49 | 2011-07-02 14:35:49 +0200 | [diff] [blame] | 113 | # list of pending blocks to free - see free() comment below |
| 114 | self._pending_free_blocks = [] |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 115 | |
| 116 | @staticmethod |
| 117 | def _roundup(n, alignment): |
| 118 | # alignment must be a power of 2 |
| 119 | mask = alignment - 1 |
| 120 | return (n + mask) & ~mask |
| 121 | |
| 122 | def _malloc(self, size): |
| 123 | # returns a large enough block -- it might be much larger |
| 124 | i = bisect.bisect_left(self._lengths, size) |
| 125 | if i == len(self._lengths): |
| 126 | length = self._roundup(max(self._size, size), mmap.PAGESIZE) |
| 127 | self._size *= 2 |
Richard Oudkerk | 84ed9a6 | 2013-08-14 15:35:41 +0100 | [diff] [blame] | 128 | util.info('allocating a new mmap of length %d', length) |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 129 | arena = Arena(length) |
| 130 | self._arenas.append(arena) |
| 131 | return (arena, 0, length) |
| 132 | else: |
| 133 | length = self._lengths[i] |
| 134 | seq = self._len_to_seq[length] |
| 135 | block = seq.pop() |
| 136 | if not seq: |
| 137 | del self._len_to_seq[length], self._lengths[i] |
| 138 | |
| 139 | (arena, start, stop) = block |
| 140 | del self._start_to_block[(arena, start)] |
| 141 | del self._stop_to_block[(arena, stop)] |
| 142 | return block |
| 143 | |
| 144 | def _free(self, block): |
| 145 | # free location and try to merge with neighbours |
| 146 | (arena, start, stop) = block |
| 147 | |
| 148 | try: |
| 149 | prev_block = self._stop_to_block[(arena, start)] |
| 150 | except KeyError: |
| 151 | pass |
| 152 | else: |
| 153 | start, _ = self._absorb(prev_block) |
| 154 | |
| 155 | try: |
| 156 | next_block = self._start_to_block[(arena, stop)] |
| 157 | except KeyError: |
| 158 | pass |
| 159 | else: |
| 160 | _, stop = self._absorb(next_block) |
| 161 | |
| 162 | block = (arena, start, stop) |
| 163 | length = stop - start |
| 164 | |
| 165 | try: |
| 166 | self._len_to_seq[length].append(block) |
| 167 | except KeyError: |
| 168 | self._len_to_seq[length] = [block] |
| 169 | bisect.insort(self._lengths, length) |
| 170 | |
| 171 | self._start_to_block[(arena, start)] = block |
| 172 | self._stop_to_block[(arena, stop)] = block |
| 173 | |
| 174 | def _absorb(self, block): |
| 175 | # deregister this block so it can be merged with a neighbour |
| 176 | (arena, start, stop) = block |
| 177 | del self._start_to_block[(arena, start)] |
| 178 | del self._stop_to_block[(arena, stop)] |
| 179 | |
| 180 | length = stop - start |
| 181 | seq = self._len_to_seq[length] |
| 182 | seq.remove(block) |
| 183 | if not seq: |
| 184 | del self._len_to_seq[length] |
| 185 | self._lengths.remove(length) |
| 186 | |
| 187 | return start, stop |
| 188 | |
Charles-François Natali | 778db49 | 2011-07-02 14:35:49 +0200 | [diff] [blame] | 189 | def _free_pending_blocks(self): |
| 190 | # Free all the blocks in the pending list - called with the lock held. |
| 191 | while True: |
| 192 | try: |
| 193 | block = self._pending_free_blocks.pop() |
| 194 | except IndexError: |
| 195 | break |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 196 | self._allocated_blocks.remove(block) |
| 197 | self._free(block) |
Charles-François Natali | 778db49 | 2011-07-02 14:35:49 +0200 | [diff] [blame] | 198 | |
| 199 | def free(self, block): |
| 200 | # free a block returned by malloc() |
| 201 | # Since free() can be called asynchronously by the GC, it could happen |
| 202 | # that it's called while self._lock is held: in that case, |
| 203 | # self._lock.acquire() would deadlock (issue #12352). To avoid that, a |
| 204 | # trylock is used instead, and if the lock can't be acquired |
| 205 | # immediately, the block is added to a list of blocks to be freed |
| 206 | # synchronously sometimes later from malloc() or free(), by calling |
| 207 | # _free_pending_blocks() (appending and retrieving from a list is not |
| 208 | # strictly thread-safe but under cPython it's atomic thanks to the GIL). |
| 209 | assert os.getpid() == self._lastpid |
| 210 | if not self._lock.acquire(False): |
| 211 | # can't acquire the lock right now, add the block to the list of |
| 212 | # pending blocks to free |
| 213 | self._pending_free_blocks.append(block) |
| 214 | else: |
| 215 | # we hold the lock |
| 216 | try: |
| 217 | self._free_pending_blocks() |
| 218 | self._allocated_blocks.remove(block) |
| 219 | self._free(block) |
| 220 | finally: |
| 221 | self._lock.release() |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 222 | |
| 223 | def malloc(self, size): |
| 224 | # return a block of right size (possibly rounded up) |
| 225 | assert 0 <= size < sys.maxsize |
| 226 | if os.getpid() != self._lastpid: |
| 227 | self.__init__() # reinitialize after fork |
Charles-François Natali | a924fc7 | 2014-05-25 14:12:12 +0100 | [diff] [blame] | 228 | with self._lock: |
| 229 | self._free_pending_blocks() |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 230 | size = self._roundup(max(size,1), self._alignment) |
| 231 | (arena, start, stop) = self._malloc(size) |
| 232 | new_stop = start + size |
| 233 | if new_stop < stop: |
| 234 | self._free((arena, new_stop, stop)) |
| 235 | block = (arena, start, new_stop) |
| 236 | self._allocated_blocks.add(block) |
| 237 | return block |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 238 | |
| 239 | # |
Richard Oudkerk | 26cdf1f | 2012-05-26 22:09:59 +0100 | [diff] [blame] | 240 | # Class representing a chunk of an mmap -- can be inherited by child process |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 241 | # |
| 242 | |
| 243 | class BufferWrapper(object): |
| 244 | |
| 245 | _heap = Heap() |
| 246 | |
| 247 | def __init__(self, size): |
| 248 | assert 0 <= size < sys.maxsize |
| 249 | block = BufferWrapper._heap.malloc(size) |
| 250 | self._state = (block, size) |
Richard Oudkerk | 84ed9a6 | 2013-08-14 15:35:41 +0100 | [diff] [blame] | 251 | util.Finalize(self, BufferWrapper._heap.free, args=(block,)) |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 252 | |
Richard Oudkerk | 26cdf1f | 2012-05-26 22:09:59 +0100 | [diff] [blame] | 253 | def create_memoryview(self): |
Benjamin Peterson | e711caf | 2008-06-11 16:44:04 +0000 | [diff] [blame] | 254 | (arena, start, stop), size = self._state |
Richard Oudkerk | 26cdf1f | 2012-05-26 22:09:59 +0100 | [diff] [blame] | 255 | return memoryview(arena.buffer)[start:start+size] |