Just a guess : wouldn't it be because the log files on disk can be made of compressed data when produced but needs to be uncompressed on consumption (of a single message) ?
2018-02-12 15:50 GMT+01:00 YuFeng Shen <v...@hotmail.com>: > Hi jan , > > I think the reason is the same as why index file using memory mapped file. > > As the memory mapped file can avoid the data copy between user and kernel > buffer space, so it can improve the performance for the index file IO > operation ,right? If it is ,why Log file cannot achieve the same > performance improvement as memory mapped index file? > > > Jacky > > > ________________________________ > From: jan <rtm4...@googlemail.com> > Sent: Saturday, February 10, 2018 8:33 PM > To: email@example.com > Subject: Re: why kafka index file use memory mapped files ,however log > file doesn't > > I'm not sure I can answer your question, but may I pose another in > return: why do you feel having a memory mapped log file would be a > good thing? > > > On 09/02/2018, YuFeng Shen <v...@hotmail.com> wrote: > > Hi Experts, > > > > We know that kafka use memory mapped files for it's index files ,however > > it's log files don't use the memory mapped files technology. > > > > May I know why index files use memory mapped files, however log files > don't > > use the same technology? > > > > > > Jacky > > > -- The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer.