WT-8643 Investigate cache stuck when a single prepared transaction tr…

…iggers eviction (#7510)

* WT-8643 Investigate cache stuck when a single prepared transaction triggers eviction

* Move the check inside the __wt_cache_eviction_check

* s_all

src/include/cache_inline.h

@@ -447,6 +447,10 @@ __wt_cache_eviction_check(WT_SESSION_IMPL *session, bool busy, bool readonly, bo
     if (F_ISSET(session, WT_SESSION_NO_RECONCILE))
         return (0);
 
+    /* If the transaction is prepared don't evict. */
+    if (F_ISSET(session->txn, WT_TXN_PREPARE))
+        return (0);
+
     /*
      * If the current transaction is keeping the oldest ID pinned, it is in the middle of an
      * operation. This may prevent the oldest ID from moving forward, leading to deadlock, so only

test/suite/test_prepare17.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python
+#
+# Public Domain 2014-present MongoDB, Inc.
+# Public Domain 2008-2014 WiredTiger, Inc.
+#
+# This is free and unencumbered software released into the public domain.
+#
+# Anyone is free to copy, modify, publish, use, compile, sell, or
+# distribute this software, either in source code form or as a compiled
+# binary, for any purpose, commercial or non-commercial, and by any
+# means.
+#
+# In jurisdictions that recognize copyright laws, the author or authors
+# of this software dedicate any and all copyright interest in the
+# software to the public domain. We make this dedication for the benefit
+# of the public at large and to the detriment of our heirs and
+# successors. We intend this dedication to be an overt act of
+# relinquishment in perpetuity of all present and future rights to this
+# software under copyright law.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+# IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+# OTHER DEALINGS IN THE SOFTWARE.
+
+import time
+import wttest
+from wtscenario import make_scenarios
+
+# test_prepare17
+class test_prepare17(wttest.WiredTigerTestCase):
+    # Set eviction triggers to 39% of cache.
+    trigger = 39
+    target = 35
+
+    conn_config = f'cache_size=1MB,' + \
+        f'eviction_trigger={trigger}, eviction_target={target},' + \
+        f'eviction_dirty_trigger={trigger}, eviction_dirty_target={target},' + \
+        f'eviction_updates_trigger={trigger}, eviction_updates_target={target},'
+
+    format_values = [
+        ('column', dict(key_format='r', value_format='S')),
+        ('int-row', dict(key_format='i', value_format='S')),
+    ]
+
+    scenarios = make_scenarios(format_values)
+
+    def test_prepare_cache_stuck_trigger(self):
+        uri = 'table:cache_stuck_on_prepared_update'
+        config = 'key_format={},value_format={}'.format(self.key_format, self.value_format)
+        self.session.create(uri, config)
+
+        cursor = self.session.open_cursor(uri, None)
+        self.session.begin_transaction()
+
+        # A 400KB update in 1MB of cache exceeds the 39% eviction threshold.
+        cursor[1] = 'a' * 400*1024
+
+        # Prepare the transaction, allowing for the updates to be evicted.
+        self.session.prepare_transaction('prepare_timestamp=' + self.timestamp_str(5))
+        self.session.timestamp_transaction('commit_timestamp=' + self.timestamp_str(5))
+        self.session.timestamp_transaction('durable_timestamp=' + self.timestamp_str(5))
+
+        # Kill the cursor to make sure the updates aren't pinned and give the WT eviction
+        # server some time to evict.
+        cursor.close()
+        time.sleep(1)
+
+        # The prepared update resides on the disk, however, as part of the process to commit the prepared update, 
+        # the page with the update is read back into the cache and the history page will be read in order to fix the stop 
+        # timestamp on any existing update in history store.
+        # Before the history page is read into the cache, it is checked whether we need to evict a page before bringing in the new page.
+        # Since the update already exceeds the 39% eviction threshold, it is possible that a cache stuck may occur.
+        # Hence, to avoid cache stuck we do not perform eviction checks(whether we need to evict a page) if the transaction is prepared.
+        self.session.commit_transaction()
+        self.session.close()