1 files changed, 27 insertions, 9 deletions

diff --git a/src/log/Log.cc b/src/log/Log.cc
index 69f6df82ecb..63d5205d9e2 100644
--- a/src/log/Log.cc
+++ b/src/log/Log.cc
@@ -31,6 +31,7 @@
 
 #include <fmt/format.h>
 #include <fmt/ostream.h>
+#include <fmt/ranges.h>
 
 #define MAX_LOG_BUF 65536
 
@@ -372,6 +373,7 @@ void Log::_flush_logbuf()
 
 void Log::_flush(EntryVector& t, bool crash)
 {
+  auto now = mono_clock::now();
   long len = 0;
   if (t.empty()) {
     assert(m_log_buf.empty());
@@ -443,10 +445,29 @@ void Log::_flush(EntryVector& t, bool crash)
       m_journald->log_entry(e);
     }
 
+    {
+      auto [it, _] = m_recent_thread_names.try_emplace(e.m_thread, now, DEFAULT_MAX_THREAD_NAMES);
+      auto& [t, names] = it->second;
+      if (names.size() == 0 || names.front() != e.m_thread_name.data()) {
+        names.push_front(e.m_thread_name.data());
+      }
+      t = now;
+    }
+
     m_recent.push_back(std::move(e));
   }
   t.clear();
 
+  for (auto it = m_recent_thread_names.begin(); it != m_recent_thread_names.end(); ) {
+    auto t = it->second.first;
+    auto since = now - t;
+    if (since > std::chrono::seconds(60*60*24)) {
+      it = m_recent_thread_names.erase(it);
+    } else {
+      ++it;
+    }
+  }
+
   _flush_logbuf();
 }
 
@@ -493,14 +514,10 @@ void Log::dump_recent()
   _flush(m_flush, false);
 
   _log_message("--- begin dump of recent events ---", true);
-  std::set<pthread_t> recent_pthread_ids;
   {
     EntryVector t;
     t.insert(t.end(), std::make_move_iterator(m_recent.begin()), std::make_move_iterator(m_recent.end()));
     m_recent.clear();
-    for (const auto& e : t) {
-      recent_pthread_ids.emplace(e.m_thread);
-    }
     _flush(t, true);
   }
 
@@ -515,14 +532,15 @@ void Log::dump_recent()
 			   m_stderr_log, m_stderr_crash), true);
 
   _log_message("--- pthread ID / name mapping for recent threads ---", true);
-  for (const auto pthread_id : recent_pthread_ids)
+  for (const auto& [tid, t_names] : m_recent_thread_names)
   {
-    char pthread_name[16] = {0}; //limited by 16B include terminating null byte.
-    ceph_pthread_getname(pthread_id, pthread_name, sizeof(pthread_name));
+    [[maybe_unused]] auto [t, names] = t_names;
     // we want the ID to be printed in the same format as we use for a log entry.
     // The reason is easier grepping.
-    _log_message(fmt::format("  {:x} / {}",
-			     tid_to_int(pthread_id), pthread_name), true);
+    auto msg = fmt::format("  {:x} / {}",
+      tid_to_int(tid),
+      fmt::join(names, ", "));
+    _log_message(msg, true);
   }
 
   _log_message(fmt::format("  max_recent {:9}", m_recent.capacity()), true);