我一直致力于一个开源项目，http://gtkworkbook.sourceforge.net/，最近遇到了一个似乎我正在进行的问题。我很确定存在堆问题，但我一直在查看这段代码，以确定它究竟是什么。
因此，简而言之，我正在做的是在使用libcsv解析器时从N指针到M指针重新分配一块内存。如果有其他列，我想将数组的最大大小增加到当前大小的2倍。这是目前的代码：
struct csv_column {
Sheet * sheet;
Cell ** array;
int & array_max;
int & array_size;
int row;
int field;
char * value;
};
static void
cb1 (void * s, size_t length, void * data) {
struct csv_column * column = (struct csv_column *) data;
int & array_max = column->array_max;
// Resize the cell array here.
if (column->field >= array_max) {
int max = (2 * array_max);
(column->array) = (Cell **) g_realloc ((column->array), max * sizeof (Cell*));
for (int ii = array_max; ii array)[column->field] == NULL)
(column->array)[column->field] = cell_new();
Cell * cell = (column->array)[column->field];
cell->set_row (cell, column->row);
cell->set_column (cell, column->field++);
cell->set_value_length (cell, s, length);
}
CsvParser::CsvParser (Workbook * wb,
FILE * log,
int verbosity,
int maxOfFields) {
this->wb = wb;
this->log = log;
this->verbosity = verbosity;
this->sizeOfFields = 0;
this->maxOfFields = maxOfFields;
this->fields = (Cell **) g_malloc (maxOfFields * sizeof (Cell*));
for (int ii = 0; ii maxOfFields; ii++)
this->fields[ii] = NULL;
}
CsvParser::~CsvParser (void) {
for (int ii = 0; ii maxOfFields; ii++) {
if (this->fields[ii])
this->fields[ii]->destroy (this->fields[ii]);
}
g_free (this->fields);
}
这是valgrind输出：
==28476== Thread 9: ==28476== Invalid read of size 8 ==28476== at 0x771AF4F: sheet_method_apply_cellarray (sheet.c:351) ==28476== by 0xD930DB7: largefile::CsvParser::run(void*) (CsvParser.cpp:147) ==28476== by 0xDD624C8: concurrent::thread_run(void*) (Thread.cpp:28) ==28476== by 0xA7B73B9: start_thread (in /lib/libpthread-2.9.so) ==28476== by 0x80DBFCC: clone (in /lib/libc-2.9.so) ==28476== Address 0xbc5d4a8 is 0 bytes inside the accessing pointer's ==28476== once-legitimate range, a block of size 160 free'd ==28476== at 0x4C25D4F: free (vg_replace_malloc.c:323) ==28476== by 0xD9314CA: largefile::cb1(void*, unsigned long, void*) (CsvParser.cpp:57) ==28476== by 0xDB42681: csv_parse (in /home/jbellone/work/gtkworkbook/lib/libcsv.so) ==28476== by 0xD930D00: largefile::CsvParser::run(void*) (CsvParser.cpp:136) ==28476== by 0xDD624C8: concurrent::thread_run(void*) (Thread.cpp:28) ==28476== by 0xA7B73B9: start_thread (in /lib/libpthread-2.9.so) ==28476== by 0x80DBFCC: clone (in /lib/libc-2.9.so) ==28476== ==28476== Invalid read of size 8 ==28476== at 0x771AF66: sheet_method_apply_cellarray (sheet.c:351) ==28476== by 0xD930DB7: largefile::CsvParser::run(void*) (CsvParser.cpp:147) ==28476== by 0xDD624C8: concurrent::thread_run(void*) (Thread.cpp:28) ==28476== by 0xA7B73B9: start_thread (in /lib/libpthread-2.9.so) ==28476== by 0x80DBFCC: clone (in /lib/libc-2.9.so) ==28476== Address 0xbc5d4a8 is 0 bytes inside the accessing pointer's ==28476== once-legitimate range, a block of size 160 free'd ==28476== at 0x4C25D4F: free (vg_replace_malloc.c:323) ==28476== by 0xD9314CA: largefile::cb1(void*, unsigned long, void*) (CsvParser.cpp:57) ==28476== by 0xDB42681: csv_parse (in /home/jbellone/work/gtkworkbook/lib/libcsv.so) ==28476== by 0xD930D00: largefile::CsvParser::run(void*) (CsvParser.cpp:136) ==28476== by 0xDD624C8: concurrent::thread_run(void*) (Thread.cpp:28) ==28476== by 0xA7B73B9: start_thread (in /lib/libpthread-2.9.so) ==28476== by 0x80DBFCC: clone (in /lib/libc-2.9.so)
sheet.c第351行
gtk_sheet_set_cell_text (GTK_SHEET (sheet->gtk_sheet),
array[ii]->row,
array[ii]->column,
array[ii]->value->str);
sheet.c的整个功能：
static void
sheet_method_apply_cellarray (Sheet * sheet,
Cell ** array,
gint size)
{
ASSERT (sheet != NULL);
g_return_if_fail (array != NULL);
gdk_threads_enter ();
/* We'll see how this performs for now. In the future we may want to go
directly into the GtkSheet structures to get a little more performance
boost (mainly because we should not have to check all the bounds each
time we want to update). */
for (gint ii = 0; ii gtk_sheet),
array[ii]->row,
array[ii]->column,
array[ii]->value->str);
if (!IS_NULLSTR (array[ii]->attributes.bgcolor->str))
sheet->range_set_background (sheet,
&array[ii]->range,
array[ii]->attributes.bgcolor->str);
if (!IS_NULLSTR (array[ii]->attributes.fgcolor->str))
sheet->range_set_foreground (sheet,
&array[ii]->range,
array[ii]->attributes.fgcolor->str);
/* Clear all of the strings */
g_string_assign (array[ii]->value, "");
g_string_assign (array[ii]->attributes.bgcolor, "");
g_string_assign (array[ii]->attributes.fgcolor, "");
}
gdk_threads_leave ();
}
CSV解析器主题
void *
CsvParser::run (void * null) {
this->running = true;
std::queue queue;
struct csv_parser csv;
struct csv_column column = {this->wb->sheet_first,
this->fields,
this->maxOfFields,
this->sizeOfFields,
0,
0,
new char [1024]};
if (csv_init (&csv, CSV_STRICT) != 0) {
std::cerr running == true) {
if (this->inputQueue.size() > 0) {
// Lock, copy, clear, unlock. - Free this up.
this->inputQueue.lock();
this->inputQueue.copy (queue);
this->inputQueue.clear();
this->inputQueue.unlock();
while (queue.size() > 0) {
std::string buf = queue.front(); queue.pop();
size_t bytes = buf.length();
if (this->running == false)
break;
if ((bytes = csv_parse (&csv, buf.c_str(), bytes, cb1, cb2, &column)) == bytes) {
if (csv_error (&csv) == CSV_EPARSE) {
std::cerr wb->sheet_first->apply_array (this->wb->sheet_first,
this->fields,
this->sizeOfFields);
if (column.row >= (column.sheet)->max_rows)
column.row = 0;
}
}
concurrent::Thread::sleep(1);
}
return NULL;
}
答案 0 :(得分：2)
我的猜测是你遇到了线程竞争状态。当您的解析器尝试使用它时，Cb1正在重新分配该数组。重新分配后，旧地址不再有效，这是您的无效读取来自的地方。您需要在阵列周围放置一个锁（可能是读取器/写入器锁）以防止遇到此问题。如果可能，请尝试运行此单线程代码以查看问题是否重现。如果不是那么它就是一个线程问题，否则它完全是另一回事。