From b00b62f0e784b5eb616868c60985292cb3a7239d Mon Sep 17 00:00:00 2001
From: Costa Tsaousis <costa@netdata.cloud>
Date: Wed, 11 Jan 2023 17:45:25 +0200
Subject: cancel ml threads on shutdown and join them on host free (#14240)

* cancel ml threads on shutdown and join them on host free

* mark them not running before joining them
---
 ml/Host.cc | 32 ++++++++++++++++++++------------
 ml/Host.h  |  9 +++++++--
 ml/ml.cc   |  9 ++++++++-
 ml/ml.h    |  1 +
 4 files changed, 36 insertions(+), 15 deletions(-)

diff --git a/ml/Host.cc b/ml/Host.cc
index 5980f610d8..a94bc2beae 100644
--- a/ml/Host.cc
+++ b/ml/Host.cc
@@ -213,7 +213,7 @@ void Host::train() {
     worker_register_job_name(WORKER_JOB_TRAINING_TRAIN, "train");
     worker_register_job_name(WORKER_JOB_TRAINING_STATS, "stats");
 
-    service_register(SERVICE_THREAD_TYPE_NETDATA, NULL, (force_quit_t )ml_stop_anomaly_detection_threads, RH, true);
+    service_register(SERVICE_THREAD_TYPE_NETDATA, NULL, (force_quit_t )ml_cancel_anomaly_detection_threads, RH, true);
 
     while (service_running(SERVICE_ML_TRAINING)) {
         auto P = TrainingQueue.pop();
@@ -293,7 +293,7 @@ void Host::detect() {
     worker_register_job_name(WORKER_JOB_DETECTION_STATS, "stats");
     worker_register_job_name(WORKER_JOB_DETECTION_RESOURCES, "resources");
 
-    service_register(SERVICE_THREAD_TYPE_NETDATA, NULL, (force_quit_t )ml_stop_anomaly_detection_threads, RH, true);
+    service_register(SERVICE_THREAD_TYPE_NETDATA, NULL, (force_quit_t )ml_cancel_anomaly_detection_threads, RH, true);
 
     heartbeat_t HB;
     heartbeat_init(&HB);
@@ -332,29 +332,37 @@ void Host::startAnomalyDetectionThreads() {
     }
 
     ThreadsRunning = true;
+    ThreadsCancelled = false;
+    ThreadsJoined = false;
 
     char Tag[NETDATA_THREAD_TAG_MAX + 1];
 
     snprintfz(Tag, NETDATA_THREAD_TAG_MAX, "TRAIN[%s]", rrdhost_hostname(RH));
-    netdata_thread_create(&TrainingThread, Tag, NETDATA_THREAD_OPTION_DEFAULT, train_main, static_cast<void *>(this));
+    netdata_thread_create(&TrainingThread, Tag, NETDATA_THREAD_OPTION_JOINABLE, train_main, static_cast<void *>(this));
 
     snprintfz(Tag, NETDATA_THREAD_TAG_MAX, "DETECT[%s]", rrdhost_hostname(RH));
-    netdata_thread_create(&DetectionThread, Tag, NETDATA_THREAD_OPTION_DEFAULT, detect_main, static_cast<void *>(this));
+    netdata_thread_create(&DetectionThread, Tag, NETDATA_THREAD_OPTION_JOINABLE, detect_main, static_cast<void *>(this));
 }
 
-void Host::stopAnomalyDetectionThreads() {
+void Host::stopAnomalyDetectionThreads(bool join) {
     if (!ThreadsRunning) {
         error("Anomaly detections threads for host %s have already been stopped.", rrdhost_hostname(RH));
         return;
     }
 
-    ThreadsRunning = false;
+    if(!ThreadsCancelled) {
+        ThreadsCancelled = true;
 
-    // Signal the training queue to stop popping-items
-    TrainingQueue.signal();
-    netdata_thread_cancel(TrainingThread);
-    // netdata_thread_join(TrainingThread, nullptr);
+        // Signal the training queue to stop popping-items
+        TrainingQueue.signal();
+        netdata_thread_cancel(TrainingThread);
+        netdata_thread_cancel(DetectionThread);
+    }
 
-    netdata_thread_cancel(DetectionThread);
-    // netdata_thread_join(DetectionThread, nullptr);
+    if(join && !ThreadsJoined) {
+        ThreadsJoined = true;
+        ThreadsRunning = false;
+        netdata_thread_join(TrainingThread, nullptr);
+        netdata_thread_join(DetectionThread, nullptr);
+    }
 }
diff --git a/ml/Host.h b/ml/Host.h
index e68ea4f050..289cb5ab7e 100644
--- a/ml/Host.h
+++ b/ml/Host.h
@@ -26,7 +26,10 @@ public:
         MLS(),
         TS(),
         HostAnomalyRate(0.0),
-        ThreadsRunning(false) {}
+        ThreadsRunning(false),
+        ThreadsCancelled(false),
+        ThreadsJoined(false)
+        {}
 
     void addChart(Chart *C);
     void removeChart(Chart *C);
@@ -36,7 +39,7 @@ public:
     void getDetectionInfoAsJson(nlohmann::json &Json) const;
 
     void startAnomalyDetectionThreads();
-    void stopAnomalyDetectionThreads();
+    void stopAnomalyDetectionThreads(bool join);
 
     void scheduleForTraining(TrainingRequest TR);
     void train();
@@ -50,6 +53,8 @@ private:
     TrainingStats TS;
     CalculatedNumber HostAnomalyRate{0.0};
     std::atomic<bool> ThreadsRunning;
+    std::atomic<bool> ThreadsCancelled;
+    std::atomic<bool> ThreadsJoined;
 
     Queue<TrainingRequest> TrainingQueue;
 
diff --git a/ml/ml.cc b/ml/ml.cc
index 2a0df8867c..461c83baae 100644
--- a/ml/ml.cc
+++ b/ml/ml.cc
@@ -156,7 +156,14 @@ void ml_start_anomaly_detection_threads(RRDHOST *RH) {
 void ml_stop_anomaly_detection_threads(RRDHOST *RH) {
     if (RH && RH->ml_host) {
         Host *H = reinterpret_cast<Host *>(RH->ml_host);
-        H->stopAnomalyDetectionThreads();
+        H->stopAnomalyDetectionThreads(true);
+    }
+}
+
+void ml_cancel_anomaly_detection_threads(RRDHOST *RH) {
+    if (RH && RH->ml_host) {
+        Host *H = reinterpret_cast<Host *>(RH->ml_host);
+        H->stopAnomalyDetectionThreads(false);
     }
 }
 
diff --git a/ml/ml.h b/ml/ml.h
index 790f881841..8bed627f5a 100644
--- a/ml/ml.h
+++ b/ml/ml.h
@@ -31,6 +31,7 @@ void ml_dimension_delete(RRDDIM *RD);
 
 void ml_start_anomaly_detection_threads(RRDHOST *RH);
 void ml_stop_anomaly_detection_threads(RRDHOST *RH);
+void ml_cancel_anomaly_detection_threads(RRDHOST *RH);
 
 char *ml_get_host_info(RRDHOST *RH);
 char *ml_get_host_runtime_info(RRDHOST *RH);
-- 
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