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New PYMALLOC_DEBUG function void _PyMalloc_DebugDumpStats(void).
This displays stats about the # of arenas, pools, blocks and bytes, to stderr, both used and reserved but unused. CAUTION: Because PYMALLOC_DEBUG is on, the debug malloc routine adds 16 bytes to each request. This makes each block appear two size classes higher than it would be if PYMALLOC_DEBUG weren't on. So far, playing with this confirms the obvious: there's a lot of activity in the "small dict" size class, but nothing in the core makes any use of the 8-byte or 16-byte classes.
1 parent de14a30 commit 7ccfadf

2 files changed

Lines changed: 98 additions & 1 deletion

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‎Include/pymem.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -102,6 +102,7 @@ DL_IMPORT(void *) _PyMalloc_DebugRealloc(void *p, size_t nbytes);
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DL_IMPORT(void) _PyMalloc_DebugFree(void *p);
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DL_IMPORT(void) _PyMalloc_DebugDumpAddress(const void *p);
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DL_IMPORT(void) _PyMalloc_DebugCheckAddress(const void *p);
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DL_IMPORT(void) _PyMalloc_DebugDumpStats(void);
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#define _PyMalloc_MALLOC _PyMalloc_DebugMalloc
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#define _PyMalloc_REALLOC _PyMalloc_DebugRealloc
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#define _PyMalloc_FREE _PyMalloc_DebugFree

‎Objects/obmalloc.c‎

Lines changed: 97 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1026,7 +1026,11 @@ _PyMalloc_DebugRealloc(void *p, size_t nbytes)
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return fresh;
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}
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void
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/* Check the forbidden bytes on both ends of the memory allocated for p.
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* If anything is wrong, print info to stderr via _PyMalloc_DebugDumpAddress,
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* and call Py_FatalError to kill the program.
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*/
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void
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_PyMalloc_DebugCheckAddress(const void *p)
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{
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const uchar *q = (const uchar *)p;
@@ -1063,6 +1067,7 @@ _PyMalloc_DebugCheckAddress(const void *p)
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Py_FatalError(msg);
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}
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/* Display info to stderr about the memory block at p. */
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void
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_PyMalloc_DebugDumpAddress(const void *p)
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{
@@ -1149,4 +1154,95 @@ _PyMalloc_DebugDumpAddress(const void *p)
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}
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}
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/* Print summary info to stderr about the state of pymalloc's structures. */
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void
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_PyMalloc_DebugDumpStats(void)
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{
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uint i;
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const uint numclasses = SMALL_REQUEST_THRESHOLD >> ALIGNMENT_SHIFT;
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uint numfreepools = 0;
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/* # of pools per class index */
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ulong numpools[SMALL_REQUEST_THRESHOLD >> ALIGNMENT_SHIFT];
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/* # of allocated blocks per class index */
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ulong numblocks[SMALL_REQUEST_THRESHOLD >> ALIGNMENT_SHIFT];
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/* # of free blocks per class index */
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ulong numfreeblocks[SMALL_REQUEST_THRESHOLD >> ALIGNMENT_SHIFT];
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ulong grandtotal; /* total # of allocated bytes */
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ulong freegrandtotal; /* total # of available bytes in used blocks */
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fprintf(stderr, "%u arenas * %d bytes/arena = %lu total bytes.\n",
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narenas, ARENA_SIZE, narenas * (ulong)ARENA_SIZE);
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fprintf(stderr, "Small block threshold = %d, in %u size classes.\n",
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SMALL_REQUEST_THRESHOLD, numclasses);
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fprintf(stderr, "pymalloc malloc+realloc called %lu times.\n",
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serialno);
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for (i = 0; i < numclasses; ++i)
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numpools[i] = numblocks[i] = numfreeblocks[i] = 0;
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/* Because empty pools aren't linked to from anything, it's easiest
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* to march over all the arenas.
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*/
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for (i = 0; i < narenas; ++i) {
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uint poolsinarena;
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uint j;
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uptr base = arenas[i];
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/* round up to pool alignment */
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poolsinarena = ARENA_SIZE / POOL_SIZE;
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if (base & (uptr)POOL_SIZE_MASK) {
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--poolsinarena;
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base &= ~(uptr)POOL_SIZE_MASK;
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base += POOL_SIZE;
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}
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if (i == narenas - 1) {
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/* current arena may have raw memory at the end */
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numfreepools += nfreepools;
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poolsinarena -= nfreepools;
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}
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/* visit every pool in the arena */
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for (j = 0; j < poolsinarena; ++j, base += POOL_SIZE) {
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poolp p = (poolp)base;
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if (p->ref.count == 0) {
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/* currently unused */
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++numfreepools;
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continue;
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}
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++numpools[p->szidx];
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numblocks[p->szidx] += p->ref.count;
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numfreeblocks[p->szidx] += p->capacity - p->ref.count;
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}
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}
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fputc('\n', stderr);
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fprintf(stderr, "Number of unused pools: %u\n", numfreepools);
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fputc('\n', stderr);
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fputs("class num bytes num pools blocks in use avail blocks\n"
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"----- --------- --------- ------------- ------------\n",
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stderr);
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grandtotal = freegrandtotal = 0;
1227+
for (i = 0; i < numclasses; ++i) {
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ulong p = numpools[i];
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ulong b = numblocks[i];
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ulong f = numfreeblocks[i];
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uint size = (i+1) << ALIGNMENT_SHIFT;
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if (p == 0) {
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assert(b == 0 && f == 0);
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continue;
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}
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fprintf(stderr, "%5u %11u %11lu %15lu %13lu\n",
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i, size, p, b, f);
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grandtotal += b * size;
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freegrandtotal += f * size;
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}
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fputc('\n', stderr);
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fprintf(stderr, "Total bytes in allocated blocks: %lu\n",
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grandtotal);
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fprintf(stderr, "Total free bytes in used pools: %lu\n",
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freegrandtotal);
1246+
}
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#endif /* PYMALLOC_DEBUG */

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