I support replacing it with JDK's ConcurrentHashMap. Maintaining a customized concurrent hash map whose algorithm is essentially the same with the implementation of a very old version of JDK is painful. The PROs listed like no boxing and linear probing have not proved to be better by any benchmark. Instead, Penghui's benchmark shows the performance is much worse.
Regarding the remove or other operations in forEach method, I believe there is a good way to resolve it and we should not do many things in the forEach callback. Thanks, Yunze On Wed, Sep 6, 2023 at 2:36 PM the tumbled <wof...@qq.com.invalid> wrote: > > > > On 2023/09/06 04:22:58 QQ wrote: > > Hi Pulsar Community, > > > > I’d like to start a discussion about whether replacing the customize util > > class like ConcurrentOpenHashMap with ConcurrentHashMap, as the performance > > of ConcurrentHashMap is better than those customize util significantly. > > Worse, these customize util class cannot ensure consistence in method > > forEach as PR https://github.com/apache/pulsar/pull/21110 shows, which is > > disquieting, although it may not cause any problem. > > > > Thanks, > > The Tumbled. > > > > The benchmark results is provided in > https://github.com/apache/pulsar/pull/20647\#issuecomment-1607257960 > <https://github.com/apache/pulsar/pull/20647%5C#issuecomment-1607257960>. > > > > However, iterators are designed to be used by only one thread at a time. > > Bear in mind that the results of aggregate status methods including size, > > isEmpty, and containsValue are typically useful only when a map is not > > undergoing concurrent updates in other threads. Otherwise the results of > > these methods reflect transient states that may be adequate for monitoring > > or estimation purposes, but not for program control. > > And I notice that ConcurrentHashMap’s forEach method do not support > thread-safety too. > It seems that the only reason left for us to replacing the customized util is > the superior performance of ConcurrentHashMap. > > Thanks, > The Tumbled.
