Leveldb lock not released

[Eddy Ilg]

Hi,

I am expericing problems with a dataset. In the log I get the message
IO error: lock /.../data/caffe/datasets/STL64noaug4_12/16000/data-leveldb/LOCK: already held by process

Checking the data-leveldb folder gives me:
-rw-r--r-- 1 ... 113M Nov 20 16:46 000005.sst
-rw-r--r-- 1 ...  68M Nov 20 16:46 000006.sst
-rw-r--r-- 1 ...    0 Dez 19 16:46 000139.log
-rw-r--r-- 1 ...   16 Dez 19 16:46 CURRENT
-rw-r--r-- 1 ...    0 Dez 19 16:46 LOCK
-rw-r--r-- 1 ...    0 Dez 19 16:46 LOG
-rw-r--r-- 1 ...   59 Dez 19 16:46 LOG.old
-rw-r--r-- 1 ... 135 Dez 19 16:46 MANIFEST-000138

So I delete everything that could have to do with the lock:
-rw-r--r-- 1 ... 113M Nov 20 16:46 000005.sst
-rw-r--r-- 1 ...  68M Nov 20 16:46 000006.sst
-rw-r--r-- 1 ...   16 Dez 19 16:46 CURRENT
-rw-r--r-- 1 ... 135 Dez 19 16:46 MANIFEST-000138

But the error still persists! I cannot use the dataset anymore... Any idea why this could be? Do I have to delete more files?

BTW: Is there any chance to convert leveldb to LMDB?


Best,



Eddy

[Sergio Guadarrama]

Are you trying to open twice the same leveldb?

There is no tool to convert a leveld to a lmdb, you will need to generate it again.

[Eddy Ilg]

You were right, my test and training used the same db. I had to produce a copy for each to make it work.

Thanks,


Eddy

[wangyi...@gmail.com]

leveldb  can just use one process to open,if you use other process to open,it will report lock file is held.
if you read the source code,you can find db_impl.cc file,Status DBImpl::Recover(VersionEdit* edit, bool *save_manifest) method,

 Status s = env_->LockFile(LockFileName(dbname_), &db_lock_);

  if (!s.ok()) {

std::cout << s.ToString();

    return s;

  }

it check whether lock file is held.

在 2014年12月19日星期五 UTC+8下午11:57:26，Eddy Ilg写道：

[Jan]

Yeah, leveldb doesn't seem to have a readonly access mode, and hence only one process can access it at a time. Which kind of sucks, as there is no real reason why it is done this way. For me it's a dealbraker, I don't use leveldb. On the other hand, lmdb can actually be opened read-only and by multiple processes simultaneously.

Jan