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Devaraj Das edited comment on HBASE-18214 at 6/23/17 11:58 PM: --------------------------------------------------------------- Looks fine but I think the lock inside {code}mapped_type& operator[](const key_type& key) {code} (in the class concurrent_map) should be the unique_lock since we are mutating the map when the key doesn't exist, no? was (Author: devaraj): Looks fine but I think the lock inside {code}mapped_type& operator[](const key_type& key) {code} should be the unique_lock since we are mutating the map when the key doesn't exist, no? > Replace the folly::AtomicHashMap usage in the RPC layer > ------------------------------------------------------- > > Key: HBASE-18214 > URL: https://issues.apache.org/jira/browse/HBASE-18214 > Project: HBase > Issue Type: Sub-task > Reporter: Devaraj Das > Assignee: Devaraj Das > Attachments: 18214-1-1.txt, 18214-1-2.txt, hbase-18214_v3.patch, > hbase-18214_v4.patch > > > In my tests, I saw that folly::AtomicHashMap usage is not appropriate for > one, rather common use case. It'd become sort of unusable (inserts would > hang) after a bunch of inserts and erases. This hashmap is used to keep track > of call-Id after a connection is set up in the RPC layer (insert a > call-id/msg pair when an RPC is sent, and erase the pair when the > corresponding response is received). Here is a simple program that will > demonstrate the issue: > {code} > folly::AtomicHashMap<int, int> f(100); > int i = 0; > while (i < 10000) { > try { > f.insert(i,100); > LOG(INFO) << "Inserted " << i << " " << f.size(); > f.erase(i); > LOG(INFO) << "Deleted " << i << " " << f.size(); > i++; > } catch (const std::exception &e) { > LOG(INFO) << "Exception " << e.what(); > break; > } > } > {code} > After poking around a little bit, it is indeed called out as a limitation > here > https://github.com/facebook/folly/blob/master/folly/docs/AtomicHashMap.md > (grep for 'erase'). Proposal is to replace this with something that will fit > in in the above usecase (thinking of using std::unordered_map). -- This message was sent by Atlassian JIRA (v6.4.14#64029)