Title
A Distributed System for Large-scale n-gram Language Models at Tencent.
Abstract
n-gram language models are widely used in language processing applications, e.g., automatic speech recognition, for ranking the candidate word sequences generated from the generator model, e.g., the acoustic model. Large n-gram models typically give good ranking results; however, they require a huge amount of memory storage. While distributing the model across multiple nodes resolves the memory issue, it nonetheless incurs a great network communication overhead and introduces a different bottleneck. In this paper, we present our distributed system developed at Tencent with novel optimization techniques for reducing the network overhead, including distributed indexing, batching and caching. They reduce the network requests and accelerate the operation on each single node. We also propose a cascade fault-tolerance mechanism which adaptively switches to small n-gram models depending on the severity of the failure. Experimental study on 9 automatic speech recognition (ASR) datasets confirms that our distributed system scales to large models efficiently, effectively and robustly. We have successfully deployed it for Tencent's WeChat ASR with the peak network traffic at the scale of 100 millions of messages per minute.
Year
DOI
Venue
2019
10.14778/3352063.3352136
PVLDB
Keywords
DocType
Volume
WeChat, distributed computing, n-gram language model, speech recognition
Journal
12
Issue
ISSN
Citations 
12
2150-8097
0
PageRank 
References 
Authors
0.34
0
7
Name
Order
Citations
PageRank
Qiang Long100.34
Wei Wang233832.88
Jinfu Deng300.68
Song Liu400.34
Wenhao Huang500.34
Fangying Chen600.68
SiFan Liu7144.04