bahman/scylla
1
0
Fork 0
Code Issues Pull Requests Actions 2 Packages Projects Releases Wiki Activity

sstables/mx/writer: yield after writing a cell

Browse Source 
With the goal of avoiding stalls on writing large collections, like
below:
    ++[0#1/1 100%] addr=0x5422d1e total=32 count=1 avg=32:
    |              seastar::backtrace<seastar::backtrace_buffer::append_backtrace_oneline()::{lambda(seastar::frame)#1}> at ./build/release/seastar/./seastar/include/seastar/util/backtrace.hh:85
    ++           - addr=0x541b6d4:
    |              seastar::backtrace_buffer::append_backtrace_oneline at ./build/release/seastar/./seastar/src/core/reactor.cc:811
    |              (inlined by) seastar::print_with_backtrace at ./build/release/seastar/./seastar/src/core/reactor.cc:838
    ++           - addr=0x541afb7:
    |              seastar::internal::cpu_stall_detector::generate_trace at ./build/release/seastar/./seastar/src/core/reactor.cc:1479
    ++           - addr=0x541b86c:
    |              seastar::internal::cpu_stall_detector::maybe_report at ./build/release/seastar/./seastar/src/core/reactor.cc:1214
    |              (inlined by) seastar::internal::cpu_stall_detector::on_signal at ./build/release/seastar/./seastar/src/core/reactor.cc:1234
    |              (inlined by) seastar::reactor::block_notifier at ./build/release/seastar/./seastar/src/core/reactor.cc:1548
    /opt/scylladb/libreloc/libc.so.6: ELF 64-bit LSB shared object, x86-64, version 1 (GNU/Linux), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=f83d43b9b4b0ed5c2bd0a1613bf33e08ee054c93, for GNU/Linux 3.2.0, not stripped

    ++           - addr=/opt/scylladb/libreloc/libc.so.6+0x1a28f:
    |              sigpending at ??:0
    ++           - addr=0x1760bf6:
    |              std::basic_string_view<signed char, std::char_traits<signed char> >::remove_prefix at /usr/lib/gcc/x86_64-redhat-linux/15/../../../../include/c++/15/string_view:302
    |              (inlined by) managed_bytes_basic_view<(mutable_view)0>::remove_prefix at ././utils/managed_bytes.hh:421
    |              (inlined by) _Z11read_simpleIlTk14FragmentedView24managed_bytes_basic_viewIL12mutable_view0EEET_RT0_ at ././utils/fragment_range.hh:365
    |              (inlined by) _ZL9get_fieldIlTk14FragmentedView24managed_bytes_basic_viewIL12mutable_view0EEQsr3stdE12is_trivial_vIT_EES3_T0_j at ././mutation/atomic_cell.hh:62
    |              (inlined by) atomic_cell_type::timestamp at ././mutation/atomic_cell.hh:103
    |              (inlined by) basic_atomic_cell_view<(mutable_view)0>::timestamp at ././mutation/atomic_cell.hh:232
    |              (inlined by) sstables::mc::writer::write_cell at ./sstables/mx/writer.cc:1101
    |              (inlined by) sstables::mc::writer::write_collection(bytes_ostream&, clustering_key_prefix const*, column_definition const&, collection_mutation_view, sstables::mc::writer::row_time_properties const&, bool)::$_0::operator() at ./sstables/mx/writer.cc:1233
    |              (inlined by) collection_mutation_view::with_deserialized<sstables::mc::writer::write_collection(bytes_ostream&, clustering_key_prefix const*, column_definition const&, collection_mutation_view, sstables::mc::writer::row_time_properties const&, bool)::$_0> at ././mutation/collection_mutation.hh:97
    |              (inlined by) sstables::mc::writer::write_collection at ./sstables/mx/writer.cc:1221
    ++           - addr=0x1677af3:
    |              sstables::mc::writer::write_cells at ./sstables/mx/writer.cc:1261
    |              (inlined by) sstables::mc::writer::write_row_body at ./sstables/mx/writer.cc:1287
    |              (inlined by) sstables::mc::writer::write_clustered at ./sstables/mx/writer.cc:1377
    |              (inlined by) _ZN8sstables2mc6writer15write_clusteredI14clustering_rowQ9ClusteredIT_EEEvRKS4_9tombstone at ./sstables/mx/writer.cc:766
    |              (inlined by) sstables::mc::writer::consume at ./sstables/mx/writer.cc:1425

Putting the yield in write_cell() instead of in write_collection() means
that writing any row benefits from the added yield point in the middle.

Refs: SCYLLADB-964

Closes scylladb/scylladb#28948
This commit is contained in:
Botond Dénes
2026-03-09 09:18:15 +02:00
committed by Patryk Jędrzejczak
parent 475220b9c9
commit 54bddeb3b5
1 changed files with 2 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
sstables/mx/writer.cc
View File

@@ -1221,6 +1221,8 @@ void writer::write_cell(bytes_ostream& writer, const clustering_key_prefix* clus
_c_stats.update_local_deletion_time(std::numeric_limits<int>::max());
}
_sst.get_stats().on_cell_write();
thread::maybe_yield();
}
void writer::write_liveness_info(bytes_ostream& writer, const row_marker& marker) {