By the way, you can try to use a memory-profiler like [1] and [2] . It would be help to find how the memory is used
Best, Xuwei Fu [1] https://github.com/jemalloc/jemalloc/wiki/Use-Case%3A-Heap-Profiling [2] https://google.github.io/tcmalloc/gperftools.html Felipe Oliveira Carvalho <felipe...@gmail.com> 于2023年9月7日周四 00:28写道： > > (a) stays pretty stable throughout the scan (stays < 1G), (b) keeps > increasing during the scan (looks linear to the number of files scanned). > > I wouldn't take this to mean a memory leak but the memory allocator not > paging out virtual memory that has been allocated throughout the scan. > Could you run your workload under a memory profiler? > > (3) Scan the same dataset twice in the same process doesn't increase the > max rss. > > Another sign this isn't a leak, just the allocator reaching a level of > memory commitment that it doesn't feel like undoing. > > -- > Felipe > > On Wed, Sep 6, 2023 at 12:56 PM Li Jin <ice.xell...@gmail.com> wrote: > > > Hello, > > > > I have been testing "What is the max rss needed to scan through ~100G of > > data in a parquet stored in gcs using Arrow C++". > > > > The current answer is about ~6G of memory which seems a bit high so I > > looked into it. What I observed during the process led me to think that > > there are some potential cache/memory issues in the dataset/parquet cpp > > code. > > > > Main observation: > > (1) As I am scanning through the dataset, I printed out (a) memory > > allocated by the memory pool from ScanOptions (b) process rss. I found > that > > while (a) stays pretty stable throughout the scan (stays < 1G), (b) keeps > > increasing during the scan (looks linear to the number of files scanned). > > (2) I tested ScanNode in Arrow as well as an in-house library that > > implements its own "S3Dataset" similar to Arrow dataset, both showing > > similar rss usage. (Which led me to think the issue is more likely to be > in > > the parquet cpp code instead of dataset code). > > (3) Scan the same dataset twice in the same process doesn't increase the > > max rss. > > > > I plan to look into the parquet cpp/dataset code but I wonder if someone > > has some clues what the issue might be or where to look at? > > > > Thanks, > > Li > > >
