Douglas Mencken wrote:
>> Could you try re-building git with the
>> NO_THREAD_SAFE_PREAD build variable set?
>
> Yeah! It works!!!
>
> --- evil/Makefile
> +++ good/Makefile
> @@ -957,6 +957,7 @@
> HAVE_PATHS_H = YesPlease
> LIBC_CONTAINS_LIBINTL = YesPlease
> HAVE_DEV_TTY = YesPlease
> + NO_THREAD_SAFE_PREAD = YesPlease
> endif
> ifeq ($(uname_S),GNU/kFreeBSD)
> NO_STRLCPY = YesPlease
>
> With this, I do have correctly working git clone.
OK, good.
You didn't mention which platform you are on; from the above Makefile
hunk, however, I can deduce that you are on *some* version of Linux.
Hmm, it doesn't seem too likely that your pread() is thread-unsafe
(possible, just unlikely), so it could be a more fundamental problem
with the threaded index-pack code (ie commit b8a2486f1 et. seq.).
However, as a first step could you try running the test program
(given below) on your system to determine if your pread() is thread-safe
or not. (gcc -I. -o test-pread test-pread.c; ./test-pread)
Also, what is the output of "uname -a".
ATB,
Ramsay Jones
-- >8 --
#include "git-compat-util.h"
#include "thread-utils.h"
#define DATA_FILE "junk.data"
#define MAX_DATA 256 * 1024
#define NUM_THREADS 3
#define TRIALS 500000
struct thread_data {
pthread_t t;
int fd;
int cnt;
int fails;
unsigned long n;
};
static struct thread_data t[NUM_THREADS+1];
int create_data_file(void)
{
int i, fd = open(DATA_FILE, O_CREAT | O_TRUNC | O_WRONLY, 0600);
if (fd < 0)
return -1;
for (i = 0; i < MAX_DATA; i++)
if (write(fd, &i, sizeof(int)) < 0) {
close(fd);
unlink(DATA_FILE);
return -1;
}
close(fd);
return 0;
}
void *read_thread(void *data)
{
struct thread_data *d = (struct thread_data *)data;
int i, j, rd;
for (i = 0; i < TRIALS; i += MAX_DATA) {
for (j = 0; j < MAX_DATA; j++) {
ssize_t sz = read(d->fd, &rd, sizeof(int));
if (sz < 0 || rd != j)
d->fails++;
d->cnt++;
}
lseek(d->fd, 0, SEEK_SET);
}
return NULL;
}
void *pread_thread(void *data)
{
struct thread_data *d = (struct thread_data *)data;
int i, j, rd;
for (i = 0; i < TRIALS; i++) {
ssize_t sz;
d->n = d->n * 1103515245 + 12345;
j = d->n % MAX_DATA;
sz = pread(d->fd, &rd, sizeof(int), j * sizeof(int));
if (sz < 0 || rd != j)
d->fails++;
d->cnt++;
}
return NULL;
}
int main(int argc, char *argv[])
{
int fd, i;
if (create_data_file() < 0) {
printf("can't create data file\n");
return 1;
}
if ((fd = open(DATA_FILE, O_RDONLY)) < 0) {
printf("can't open data file\n");
unlink(DATA_FILE);
return 1;
}
for (i = 0; i < NUM_THREADS+1; i++) {
int ret;
t[i].fd = fd;
t[i].cnt = 0;
t[i].fails = 0;
t[i].n = i * 16381;
ret = pthread_create(&t[i].t, NULL,
(i == 0) ? read_thread : pread_thread,
&t[i]);
if (ret) {
printf("can't create thread %d (%s)\n", i,
strerror(ret));
unlink(DATA_FILE);
return 1;
}
}
for (i = 0; i < NUM_THREADS+1; i++)
pthread_join(t[i].t, NULL);
close(fd);
for (i = 0; i < NUM_THREADS+1; i++)
printf("%2d: trials %d, failed %d\n", i, t[i].cnt, t[i].fails);
unlink(DATA_FILE);
return 0;
}
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