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30 .TH MALLOC_INFO 3 2012\-04\-28 GNU "Linux Programmer's Manual"
32 malloc_info \- export malloc state to a stream
35 \fB#include <malloc.h>\fP
37 \fBint malloc_info(int \fP\fIoptions\fP\fB, FILE *\fP\fIfp\fP\fB);\fP
40 The \fBmalloc_info\fP() function exports an XML string that describes the
41 current state of the memory\-allocation implementation in the caller. The
42 string is printed on the file stream \fIfp\fP. The exported string includes
43 information about all arenas (see \fBmalloc\fP(3)).
45 As currently implemented, \fIoptions\fP must be zero.
47 \fBmalloc_info\fP() は成功すると 0 を返す。エラーの場合は \-1 を返す。
51 \fIoptions\fP was nonzero.
53 \fBmalloc_info\fP() は glibc バージョン 2.10 で追加された。
57 The memory\-allocation information is provided as an XML string (rather than
58 a C structure) because the information may change over time (according to
59 changes in the underlying implementation). The output XML string includes a
62 The \fBopen_memstream\fP(3) function can be used to send the output of
63 \fBmalloc_info\fP() directly into a buffer in memory, rather than to a file.
65 The \fBmalloc_info\fP() function is designed to address deficiencies in
66 \fBmalloc_stats\fP(3) and \fBmallinfo\fP(3).
68 The program below takes up to four command\-line arguments, of which the
69 first three are mandatory. The first argument specifies the number of
70 threads that the program should create. All of the threads, including the
71 main thread, allocate the number of blocks of memory specified by the second
72 argument. The third argument controls the size of the blocks to be
73 allocated. The main thread creates blocks of this size, the second thread
74 created by the program allocates blocks of twice this size, the third thread
75 allocates blocks of three times this size, and so on.
77 The program calls \fBmalloc_info\fP() twice to display the memory\-allocation
78 state. The first call takes place before any threads are created or memory
79 allocated. The second call is performed after all threads have allocated
82 In the following example, the command\-line arguments specify the creation of
83 one additional thread, and both the main thread and the additional thread
84 allocate 10000 blocks of memory. After the blocks of memory have been
85 allocated, \fBmalloc_info\fP() shows the state of two allocation arenas.
89 $ \fBgetconf GNU_LIBC_VERSION\fP
91 $ \fB./a.out 1 10000 100\fP
92 ============ Before allocating blocks ============
97 <total type="fast" count="0" size="0"/>
98 <total type="rest" count="0" size="0"/>
99 <system type="current" size="135168"/>
100 <system type="max" size="135168"/>
101 <aspace type="total" size="135168"/>
102 <aspace type="mprotect" size="135168"/>
104 <total type="fast" count="0" size="0"/>
105 <total type="rest" count="0" size="0"/>
106 <system type="current" size="135168"/>
107 <system type="max" size="135168"/>
108 <aspace type="total" size="135168"/>
109 <aspace type="mprotect" size="135168"/>
112 ============ After allocating blocks ============
117 <total type="fast" count="0" size="0"/>
118 <total type="rest" count="0" size="0"/>
119 <system type="current" size="1081344"/>
120 <system type="max" size="1081344"/>
121 <aspace type="total" size="1081344"/>
122 <aspace type="mprotect" size="1081344"/>
127 <total type="fast" count="0" size="0"/>
128 <total type="rest" count="0" size="0"/>
129 <system type="current" size="1032192"/>
130 <system type="max" size="1032192"/>
131 <aspace type="total" size="1032192"/>
132 <aspace type="mprotect" size="1032192"/>
134 <total type="fast" count="0" size="0"/>
135 <total type="rest" count="0" size="0"/>
136 <system type="current" size="2113536"/>
137 <system type="max" size="2113536"/>
138 <aspace type="total" size="2113536"/>
139 <aspace type="mprotect" size="2113536"/>
152 static size_t blockSize;
153 static int numThreads, numBlocks;
155 #define errExit(msg) do { perror(msg); exit(EXIT_FAILURE); \e
159 thread_func(void *arg)
164 /* The multiplier \(aq(2 + tn)\(aq ensures that each thread (including
165 the main thread) allocates a different amount of memory */
167 for (j = 0; j < numBlocks; j++)
168 if (malloc(blockSize * (2 + tn)) == NULL)
169 errExit("malloc\-thread");
171 sleep(100); /* Sleep until main thread terminates */
176 main(int argc, char *argv[])
178 int j, tn, sleepTime;
183 "%s num\-threads num\-blocks block\-size [sleep\-time]\en",
188 numThreads = atoi(argv[1]);
189 numBlocks = atoi(argv[2]);
190 blockSize = atoi(argv[3]);
191 sleepTime = (argc > 4) ? atoi(argv[4]) : 0;
193 thr = calloc(numThreads, sizeof(pthread_t));
197 printf("============ Before allocating blocks ============\en");
198 malloc_info(0, stdout);
200 /* Create threads that allocate different amounts of memory */
202 for (tn = 0; tn < numThreads; tn++) {
203 errno = pthread_create(&thr[tn], NULL, thread_func,
206 errExit("pthread_create");
208 /* If we add a sleep interval after the start\-up of each
209 thread, the threads likely won\(aqt contend for malloc
210 mutexes, and therefore additional arenas won\(aqt be
211 allocated (see malloc(3)). */
217 /* The main thread also allocates some memory */
219 for (j = 0; j < numBlocks; j++)
220 if (malloc(blockSize) == NULL)
223 sleep(2); /* Give all threads a chance to
224 complete allocations */
226 printf("\en============ After allocating blocks ============\en");
227 malloc_info(0, stdout);
233 \fBmallinfo\fP(3), \fBmalloc\fP(3), \fBmalloc_stats\fP(3), \fBmallopt\fP(3),
234 \fBopen_memstream\fP(3)
236 この man ページは Linux \fIman\-pages\fP プロジェクトのリリース 3.50 の一部
237 である。プロジェクトの説明とバグ報告に関する情報は
238 http://www.kernel.org/doc/man\-pages/ に書かれている。