Draft xxx

presto-native-execution/presto_cpp/main/common/Counters.cpp

@@ -43,6 +43,39 @@ void registerPrestoMetrics() {
       90,
       99,
       100);
+  // Tracks http client transaction create delay in range of [0, 250] with
+  // 50 buckets and reports P50, P90, P99, and P100.
+  DEFINE_HISTOGRAM_METRIC(
+      kCounterHTTPClientNumIdleSessions,
+      5,
+      0,
+      250,
+      50,
+      90,
+      99,
+      100);
+  // Tracks http client transaction create delay in range of [0, 250] with
+  // 50 buckets and reports P50, P90, P99, and P100.
+  DEFINE_HISTOGRAM_METRIC(
+      kCounterHTTPClientNumActiveNonFullSessions,
+      5,
+      0,
+      250,
+      50,
+      90,
+      99,
+      100);
+  // Tracks http client transaction create delay in range of [0, 250] with
+  // 50 buckets and reports P50, P90, P99, and P100.
+  DEFINE_HISTOGRAM_METRIC(
+      kCounterHTTPClientNumFullSessions,
+      5,
+      0,
+      250,
+      50,
+      90,
+      99,
+      100);
   DEFINE_METRIC(kCounterNumQueryContexts, facebook::velox::StatType::AVG);
   DEFINE_METRIC(kCounterNumTasks, facebook::velox::StatType::AVG);
   DEFINE_METRIC(kCounterNumTasksBytesProcessed, facebook::velox::StatType::AVG);

presto-native-execution/presto_cpp/main/common/Counters.h

@@ -43,6 +43,12 @@ constexpr folly::StringPiece kCounterHttpClientNumConnectionsCreated{
     "presto_cpp.http.client.num_connections_created"};
 constexpr folly::StringPiece kCounterHTTPClientTransactionCreateDelay{
     "presto_cpp.http.client.transaction_create_delay_ms"};
+constexpr folly::StringPiece kCounterHTTPClientNumIdleSessions{
+    "presto_cpp.http.client.num_idle_sessions"};
+constexpr folly::StringPiece kCounterHTTPClientNumActiveNonFullSessions{
+    "presto_cpp.http.num_active_non_full_sessions"};
+constexpr folly::StringPiece kCounterHTTPClientNumFullSessions{
+    "presto_cpp.http.client.num_full_sessions"};
 /// Peak number of bytes queued in PrestoExchangeSource waiting for consume.
 constexpr folly::StringPiece kCounterExchangeSourcePeakQueuedBytes{
     "presto_cpp.exchange_source_peak_queued_bytes"};

presto-native-execution/presto_cpp/main/http/HttpClient.cpp

@@ -442,6 +442,15 @@ void HttpClient::initSessionPool() {
 folly::SemiFuture<proxygen::HTTPTransaction*> HttpClient::createTransaction(
     proxygen::HTTPTransactionHandler* handler) {
   eventBase_->dcheckIsInEventBaseThread();
+  RECORD_HISTOGRAM_METRIC_VALUE(
+      kCounterHTTPClientNumIdleSessions,
+      sessionPool_->getNumIdleSessions());
+  RECORD_HISTOGRAM_METRIC_VALUE(
+      kCounterHTTPClientNumActiveNonFullSessions,
+      sessionPool_->getNumActiveNonFullSessions());
+  RECORD_HISTOGRAM_METRIC_VALUE(
+      kCounterHTTPClientNumFullSessions,
+      sessionPool_->getNumFullSessions());
   if (auto* txn = sessionPool_->getTransaction(handler)) {
     VLOG(3) << "Reuse same thread connection to " << address_.describe();
     return folly::makeSemiFuture(txn);