{"action":"created","issue":{"url":"https://api.github.com/repos/chainer/chainer/issues/3529","repository_url":"https://api.github.com/repos/chainer/chainer","labels_url":"https://api.github.com/repos/chainer/chainer/issues/3529/labels{/name}","comments_url":"https://api.github.com/repos/chainer/chainer/issues/3529/comments","events_url":"https://api.github.com/repos/chainer/chainer/issues/3529/events","html_url":"https://github.com/chainer/chainer/issues/3529","id":263900820,"number":3529,"title":"NaN is detected on backward computation of ConnectionistTemporalClassification","user":{"login":"synetkim","id":12687120,"avatar_url":"https://avatars3.githubusercontent.com/u/12687120?v=4","gravatar_id":"","url":"https://api.github.com/users/synetkim","html_url":"https://github.com/synetkim","followers_url":"https://api.github.com/users/synetkim/followers","following_url":"https://api.github.com/users/synetkim/following{/other_user}","gists_url":"https://api.github.com/users/synetkim/gists{/gist_id}","starred_url":"https://api.github.com/users/synetkim/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/synetkim/subscriptions","organizations_url":"https://api.github.com/users/synetkim/orgs","repos_url":"https://api.github.com/users/synetkim/repos","events_url":"https://api.github.com/users/synetkim/events{/privacy}","received_events_url":"https://api.github.com/users/synetkim/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":3,"created_at":"2017-10-09T13:45:48Z","updated_at":"2018-05-06T08:37:13Z","closed_at":null,"author_association":"NONE","body":"Hello.\r\n\r\nAfter several epochs, NaN occurred on backward computation of CTC. \r\nMy training loop and optimizer is like below:\r\n\r\nopt = optimizers.AdaDelta(rho=0.95, eps=1e-8)\r\n\r\n    -. training Epoch loop\r\n        ...\r\n        opt.setup(model)\r\n        opt.add_hook(chainer.optimizer.GradientClipping(2))\r\n        ...\r\n       -.  training bach loop\r\n             ...\r\n            <forward process> \r\n             ...\r\n            opt.target.cleargrads()\r\n            loss.backward()\r\n            loss.unchain_backward()\r\n            opt.update()\r\n            loss = chainer.Variable(xp.zeros((), dtype=np.float32))\r\n\r\n\r\n\r\n* Conditions\r\n  - Chainer version: 3.0.0rc1\r\n  - CuPy version: 1.0.3\r\n  - OS/Platform: Ubuntu14.04\r\n  - CUDA/cuDNN version: 8.0 / 6.0\r\n  - etc.\r\n\r\n\r\n\r\nThank you for your cooperation!\r\n\r\n"},"comment":{"url":"https://api.github.com/repos/chainer/chainer/issues/comments/386863397","html_url":"https://github.com/chainer/chainer/issues/3529#issuecomment-386863397","issue_url":"https://api.github.com/repos/chainer/chainer/issues/3529","id":386863397,"user":{"login":"stale[bot]","id":26384082,"avatar_url":"https://avatars3.githubusercontent.com/in/1724?v=4","gravatar_id":"","url":"https://api.github.com/users/stale%5Bbot%5D","html_url":"https://github.com/apps/stale","followers_url":"https://api.github.com/users/stale%5Bbot%5D/followers","following_url":"https://api.github.com/users/stale%5Bbot%5D/following{/other_user}","gists_url":"https://api.github.com/users/stale%5Bbot%5D/gists{/gist_id}","starred_url":"https://api.github.com/users/stale%5Bbot%5D/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/stale%5Bbot%5D/subscriptions","organizations_url":"https://api.github.com/users/stale%5Bbot%5D/orgs","repos_url":"https://api.github.com/users/stale%5Bbot%5D/repos","events_url":"https://api.github.com/users/stale%5Bbot%5D/events{/privacy}","received_events_url":"https://api.github.com/users/stale%5Bbot%5D/received_events","type":"Bot","site_admin":false},"created_at":"2018-05-06T08:37:13Z","updated_at":"2018-05-06T08:37:13Z","author_association":"NONE","body":"This issue has been automatically marked as stale because it has not had recent activity. It will be closed after 30 days if no further activity occurs. Thank you for your contributions.\n"}}
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