Index: modules/core/src/test/java/org/apache/ignite/internal/processors/cache/persistence/CheckpointFakeBlockingRepoducer.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/modules/core/src/test/java/org/apache/ignite/internal/processors/cache/persistence/CheckpointFakeBlockingRepoducer.java b/modules/core/src/test/java/org/apache/ignite/internal/processors/cache/persistence/CheckpointFakeBlockingRepoducer.java
new file mode 100644
--- /dev/null	(date 1625343626415)
+++ b/modules/core/src/test/java/org/apache/ignite/internal/processors/cache/persistence/CheckpointFakeBlockingRepoducer.java	(date 1625343626415)
@@ -0,0 +1,89 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.ignite.internal.processors.cache.persistence;
+
+import org.apache.ignite.cache.CacheAtomicityMode;
+import org.apache.ignite.cache.CacheMode;
+import org.apache.ignite.cluster.ClusterState;
+import org.apache.ignite.configuration.CacheConfiguration;
+import org.apache.ignite.configuration.DataRegionConfiguration;
+import org.apache.ignite.configuration.DataStorageConfiguration;
+import org.apache.ignite.configuration.IgniteConfiguration;
+import org.apache.ignite.internal.IgniteEx;
+import org.apache.ignite.testframework.ListeningTestLogger;
+import org.apache.ignite.testframework.LogListener;
+import org.apache.ignite.testframework.junits.common.GridCommonAbstractTest;
+import org.junit.Test;
+
+/**
+ */
+public class CheckpointFakeBlockingRepoducer extends GridCommonAbstractTest {
+    /** Failure handler timeout. */
+    public static final int FAILURE_HANDLER_TIMEOUT = 10000;
+
+    /** Checkpoint frequency. */
+    public static final int CHECKPOINT_FREQUENCY = FAILURE_HANDLER_TIMEOUT * 2;
+
+    /** Test logger. */
+    private final ListeningTestLogger testLog = new ListeningTestLogger(log);
+    /**
+     * {@inheritDoc}
+     */
+    @Override protected IgniteConfiguration getConfiguration(String igniteInstanceName) throws Exception {
+        return super.getConfiguration(igniteInstanceName)
+            .setFailureDetectionTimeout(FAILURE_HANDLER_TIMEOUT)
+            .setDataStorageConfiguration(new DataStorageConfiguration()
+                    .setDefaultDataRegionConfiguration(new DataRegionConfiguration()
+                        .setPersistenceEnabled(true))
+                .setCheckpointFrequency(CHECKPOINT_FREQUENCY))
+            .setCacheConfiguration(new CacheConfiguration<>(DEFAULT_CACHE_NAME)
+                .setCacheMode(CacheMode.REPLICATED)
+                .setAtomicityMode(CacheAtomicityMode.TRANSACTIONAL))
+            .setGridLogger(testLog);
+    }
+
+    /** {@inheritDoc} */
+    @Override protected void afterTest() throws Exception {
+        stopAllGrids();
+
+        cleanPersistenceDir();
+    }
+
+    /** {@inheritDoc} */
+    @Override protected void beforeTest() throws Exception {
+        cleanPersistenceDir();
+    }
+
+    /** */
+    @Test
+    public void test() throws Exception {
+        LogListener blockListener = LogListener.matches("Blocked system-critical thread has been detected. " +
+            "This can lead to cluster-wide undefined behaviour [workerName=db-checkpoint-thread")
+            .build();
+
+        testLog.registerListener(blockListener);
+
+        IgniteEx ig = startGrid(0);
+        ig.cluster().state(ClusterState.ACTIVE);
+
+        awaitPartitionMapExchange();
+
+        assertFalse("Blocked system-critical thread has been detected: 'db-checkpoint-thread'",
+            blockListener.check(CHECKPOINT_FREQUENCY * 3));
+    }
+}
Index: modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/checkpoint/Checkpointer.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/checkpoint/Checkpointer.java b/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/checkpoint/Checkpointer.java
--- a/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/checkpoint/Checkpointer.java	(revision 468c41f8410289ec14a6326ae7af05c1d5aa7055)
+++ b/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/checkpoint/Checkpointer.java	(date 1625343398258)
@@ -815,6 +815,8 @@
                     try {
                         wait(remaining);
 
+                        log.warning(">>>>>> Heartbeat after wait: " + heartbeatTs());
+
                         remaining = U.nanosToMillis(scheduledCp.nextCpNanos() - System.nanoTime());
                     }
                     finally {
Index: modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/checkpoint/CheckpointContextImpl.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/checkpoint/CheckpointContextImpl.java b/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/checkpoint/CheckpointContextImpl.java
--- a/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/checkpoint/CheckpointContextImpl.java	(revision 468c41f8410289ec14a6326ae7af05c1d5aa7055)
+++ b/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/checkpoint/CheckpointContextImpl.java	(date 1625343398249)
@@ -101,7 +101,16 @@
             try {
                 GridFutureAdapter<?> res = new GridFutureAdapter<>();
 
-                res.listen(fut -> heartbeatUpdater.updateHeartbeat());
+                res.listen(fut -> {
+                    try {
+                        Thread.sleep(10);
+                    }
+                    catch (InterruptedException e) {
+                        // Ignore.
+                    }
+
+                    heartbeatUpdater.updateHeartbeat();
+                });
 
                 asyncRunner.execute(U.wrapIgniteFuture(cmd, res));