Thursday, December 20, 2012

git hangs after "Resolving deltas"

Have had a funy problem with Git. I suppose it's proxy-related. Writing it down, because sure that will have the same problem some time again. Also hope it will help to people who are also suffering with it.

As a precondition, I have a git with following in '.gitconfig':


When I tried to clone repository I've got this:

$ git clone
Cloning into 'caliper'...
remote: Counting objects: 3298, done.
remote: Finding sources: 100% (3298/3298), done.
remote: Total 3298 (delta 1755)
Receiving objects: 100% (3298/3298), 7.14 MiB | 1.94 MiB/s, done.
Resolving deltas: 100% (1755/1755), done.

And then nothing, it just hangs. If you go and have a look, you can see that files are downloaded, but not unpacked. As all other people on Internet, I have no idea why that is happening, but eventually I have found a way to get files out of it.

When it hangs, just kill the process with Ctrl+C and run this command in repository folder:

$ git fsck
notice: HEAD points to an unborn branch (master)
Checking object directories: 100% (256/256), done.
Checking objects: 100% (3298/3298), done.
notice: No default references
dangling commit 2916d1238ca0f4adecbda580ef4329a649fc777c
Now just merge that dangling commit:
$ git merge 2916d1238ca0f4adecbda580ef4329a649fc777c
and from now on you can enjoy repository content in any way you want.

Thursday, December 13, 2012

File.setLastModified & File.lastModified

Have observed interesting behavior of File.lastModified file property on Linux. Basically, my problem was that I was incrementing the value of that property by 1 in one thread and monitoring the change in the other thread. And apparently no change in property's value happened, the other thread did not see increment. After some time trying to make it work, I realized that I have to increment it at least by a 1000 to make the change visible.

Wondering why that is happening, I have had a look at JDK source code and that's what I found:

Java_java_io_UnixFileSystem_getLastModifiedTime(JNIEnv *env, jobject this,
                                                jobject file)
    jlong rv = 0;

    WITH_FIELD_PLATFORM_STRING(env, file, ids.path, path) {
        struct stat64 sb;
        if (stat64(path, &sb) == 0) {
            rv = 1000 * (jlong)sb.st_mtime;
    } END_PLATFORM_STRING(env, path);
    return rv;

What happens is that on Linux File.lastModified has 1sec resolution and simply ignores milliseconds. I'm not an expert in Linux programming, so not sure is there any way get that time with millisecond resolution on Linux. Assume it should be possible because 'setLastModified' seems like is working as it is expected to work - sets modification time with millisecond resolution (you can find the source code in 'UnixFileSystem_md.c').

So, just a nice thing to remember: when you work with files on Linux, you may not see change in File.lastModified when it's value updated for less than 1000ms.