Import wiredtiger: 0626020133546d8e475e63522f49840c33a250d6 from branch mongodb-5.0

ref: 593ae41db7..0626020133
for: 4.9.0

WT-6671       Save the checkpoint snapshot that is used to take checkpoint in the metadata
WT-6763       Fix freeing update on the chain when insert fail after inserting to the update chain
WT-6793       Organize code statistics Evergreen tasks
WT-6806       Back off aggressive abort in random_directio

15 files changed, 226 insertions, 47 deletions

diff --git a/src/third_party/wiredtiger/dist/s_string.ok b/src/third_party/wiredtiger/dist/s_string.ok
index 6364398f6ff..be6ae0893fe 100644
--- a/src/third_party/wiredtiger/dist/s_string.ok
+++ b/src/third_party/wiredtiger/dist/s_string.ok
@@ -1269,6 +1269,7 @@ struct
 structs
 su
 subdirectory
+subget
 subgetraw
 subgets
 subinit
diff --git a/src/third_party/wiredtiger/import.data b/src/third_party/wiredtiger/import.data
index 3a42a06b1fd..7c33a4bc909 100644
--- a/src/third_party/wiredtiger/import.data
+++ b/src/third_party/wiredtiger/import.data
@@ -2,5 +2,5 @@
     "vendor": "wiredtiger",
     "github": "wiredtiger/wiredtiger.git",
     "branch": "mongodb-5.0",
-    "commit": "593ae41db7c2e454201f9f0539d8c74685f3242b"
+    "commit": "0626020133546d8e475e63522f49840c33a250d6"
 }
diff --git a/src/third_party/wiredtiger/src/btree/row_modify.c b/src/third_party/wiredtiger/src/btree/row_modify.c
index caef5a88c52..3b10493780f 100644
--- a/src/third_party/wiredtiger/src/btree/row_modify.c
+++ b/src/third_party/wiredtiger/src/btree/row_modify.c
@@ -54,14 +54,14 @@ __wt_row_modify(WT_CURSOR_BTREE *cbt, const WT_ITEM *key, const WT_ITEM *value,
     size_t ins_size, upd_size;
     uint32_t ins_slot;
     u_int i, skipdepth;
-    bool logged;
+    bool inserted_to_update_chain, logged;
 
     ins = NULL;
     page = cbt->ref->page;
     session = CUR2S(cbt);
     last_upd = NULL;
     upd = upd_arg;
-    logged = false;
+    inserted_to_update_chain = logged = false;
 
     /*
      * We should have one of the following:
@@ -206,6 +206,8 @@ __wt_row_modify(WT_CURSOR_BTREE *cbt, const WT_ITEM *key, const WT_ITEM *value,
           session, page, cbt->ins_head, cbt->ins_stack, &ins, ins_size, skipdepth, exclusive));
     }
 
+    inserted_to_update_chain = true;
+
     if (logged && modify_type != WT_UPDATE_RESERVE) {
         WT_ERR(__wt_txn_log_op(session, cbt));
         /*
@@ -224,7 +226,7 @@ err:
             __wt_txn_unmodify(session);
         __wt_free(session, ins);
         cbt->ins = NULL;
-        if (upd_arg == NULL)
+        if (upd_arg == NULL && !inserted_to_update_chain)
             __wt_free(session, upd);
         if (last_upd != NULL)
             last_upd->next = NULL;
diff --git a/src/third_party/wiredtiger/src/config/config.c b/src/third_party/wiredtiger/src/config/config.c
index de6e7c4e0b4..ec7fa076150 100644
--- a/src/third_party/wiredtiger/src/config/config.c
+++ b/src/third_party/wiredtiger/src/config/config.c
@@ -728,3 +728,17 @@ __wt_config_subgets(
 
     return (__wt_config_subgetraw(session, cfg, &key_item, value));
 }
+
+/*
+ * __wt_config_subget_next --
+ *     Get the value for a given key from a config string and set the processed value in the given
+ *     key structure. This is useful for unusual case of dealing with list in config string.
+ */
+int
+__wt_config_subget_next(WT_CONFIG *conf, WT_CONFIG_ITEM *key)
+{
+    WT_CONFIG_ITEM value;
+    WT_RET(__config_next(conf, key, &value));
+    __config_process_value(key);
+    return (0);
+}
diff --git a/src/third_party/wiredtiger/src/conn/conn_handle.c b/src/third_party/wiredtiger/src/conn/conn_handle.c
index f0d861d16b4..9668e8a26bc 100644
--- a/src/third_party/wiredtiger/src/conn/conn_handle.c
+++ b/src/third_party/wiredtiger/src/conn/conn_handle.c
@@ -131,6 +131,9 @@ __wt_connection_destroy(WT_CONNECTION_IMPL *conn)
     __wt_free(session, conn->dhhash);
     __wt_free(session, conn->fhhash);
 
+    /* Free allocated recovered checkpoint snapshot memory */
+    __wt_free(session, conn->recovery_ckpt_snapshot);
+
     /* Free allocated memory. */
     __wt_free(session, conn->cfg);
     __wt_free(session, conn->debug_ckpt);
diff --git a/src/third_party/wiredtiger/src/include/connection.h b/src/third_party/wiredtiger/src/include/connection.h
index a5a642fa5b0..3520b3b3941 100644
--- a/src/third_party/wiredtiger/src/include/connection.h
+++ b/src/third_party/wiredtiger/src/include/connection.h
@@ -266,6 +266,11 @@ struct __wt_connection_impl {
 
     WT_TXN_GLOBAL txn_global; /* Global transaction state */
 
+    /* Recovery checkpoint snapshot details saved in the metadata file */
+    uint64_t recovery_ckpt_snap_min, recovery_ckpt_snap_max;
+    uint64_t *recovery_ckpt_snapshot;
+    uint32_t recovery_ckpt_snapshot_count;
+
     WT_RWLOCK hot_backup_lock; /* Hot backup serialization */
     uint64_t hot_backup_start; /* Clock value of most recent checkpoint needed by hot backup */
     char **hot_backup_list;    /* Hot backup file list */
diff --git a/src/third_party/wiredtiger/src/include/extern.h b/src/third_party/wiredtiger/src/include/extern.h
index 9729b79b06d..e0c268aacf8 100644
--- a/src/third_party/wiredtiger/src/include/extern.h
+++ b/src/third_party/wiredtiger/src/include/extern.h
@@ -396,6 +396,8 @@ extern int __wt_config_merge(WT_SESSION_IMPL *session, const char **cfg, const c
   WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result));
 extern int __wt_config_next(WT_CONFIG *conf, WT_CONFIG_ITEM *key, WT_CONFIG_ITEM *value)
   WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result));
+extern int __wt_config_subget_next(WT_CONFIG *conf, WT_CONFIG_ITEM *key)
+  WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result));
 extern int __wt_config_subgetraw(WT_SESSION_IMPL *session, WT_CONFIG_ITEM *cfg, WT_CONFIG_ITEM *key,
   WT_CONFIG_ITEM *value) WT_GCC_FUNC_DECL_ATTRIBUTE((warn_unused_result));
 extern int __wt_config_subgets(WT_SESSION_IMPL *session, WT_CONFIG_ITEM *cfg, const char *key,
diff --git a/src/third_party/wiredtiger/src/include/meta.h b/src/third_party/wiredtiger/src/include/meta.h
index 2bda37b02c3..9e274e9f3cc 100644
--- a/src/third_party/wiredtiger/src/include/meta.h
+++ b/src/third_party/wiredtiger/src/include/meta.h
@@ -33,11 +33,16 @@
 #define WT_HS_FILE "WiredTigerHS.wt"     /* History store table */
 #define WT_HS_URI "file:WiredTigerHS.wt" /* History store table URI */
 
-#define WT_SYSTEM_PREFIX "system:"               /* System URI prefix */
-#define WT_SYSTEM_CKPT_TS "checkpoint_timestamp" /* Checkpoint timestamp name */
-#define WT_SYSTEM_CKPT_URI "system:checkpoint"   /* Checkpoint timestamp URI */
-#define WT_SYSTEM_OLDEST_TS "oldest_timestamp"   /* Oldest timestamp name */
-#define WT_SYSTEM_OLDEST_URI "system:oldest"     /* Oldest timestamp URI */
+#define WT_SYSTEM_PREFIX "system:"                               /* System URI prefix */
+#define WT_SYSTEM_CKPT_TS "checkpoint_timestamp"                 /* Checkpoint timestamp name */
+#define WT_SYSTEM_CKPT_URI "system:checkpoint"                   /* Checkpoint timestamp URI */
+#define WT_SYSTEM_OLDEST_TS "oldest_timestamp"                   /* Oldest timestamp name */
+#define WT_SYSTEM_OLDEST_URI "system:oldest"                     /* Oldest timestamp URI */
+#define WT_SYSTEM_CKPT_SNAPSHOT "snapshots"                      /* List of snapshots */
+#define WT_SYSTEM_CKPT_SNAPSHOT_MIN "snapshot_min"               /* Snapshot minimum */
+#define WT_SYSTEM_CKPT_SNAPSHOT_MAX "snapshot_max"               /* Snapshot maximum */
+#define WT_SYSTEM_CKPT_SNAPSHOT_COUNT "snapshot_count"           /* Snapshot count */
+#define WT_SYSTEM_CKPT_SNAPSHOT_URI "system:checkpoint_snapshot" /* Checkpoint snapshot URI */
 #define WT_SYSTEM_BASE_WRITE_GEN_URI "system:checkpoint_base_write_gen" /* Base write gen URI */
 #define WT_SYSTEM_BASE_WRITE_GEN "base_write_gen"                       /* Base write gen name */
 
diff --git a/src/third_party/wiredtiger/src/meta/meta_ckpt.c b/src/third_party/wiredtiger/src/meta/meta_ckpt.c
index d27d6203baf..aa9191bdc6a 100644
--- a/src/third_party/wiredtiger/src/meta/meta_ckpt.c
+++ b/src/third_party/wiredtiger/src/meta/meta_ckpt.c
@@ -947,13 +947,16 @@ __wt_meta_sysinfo_set(WT_SESSION_IMPL *session)
 {
     WT_DECL_ITEM(buf);
     WT_DECL_RET;
+    WT_TXN *txn;
     WT_TXN_GLOBAL *txn_global;
     wt_timestamp_t oldest_timestamp;
+    uint32_t snap_count;
     char hex_timestamp[WT_TS_HEX_STRING_SIZE];
 
     txn_global = &S2C(session)->txn_global;
 
-    WT_ERR(__wt_scr_alloc(session, 0, &buf));
+    txn = session->txn;
+    WT_ERR(__wt_scr_alloc(session, 1024, &buf));
     /*
      * We need to record the timestamp of the checkpoint in the metadata. The timestamp value is set
      * at a higher level, either in checkpoint or in recovery.
@@ -991,6 +994,21 @@ __wt_meta_sysinfo_set(WT_SESSION_IMPL *session)
         WT_ERR(__wt_metadata_update(session, WT_SYSTEM_OLDEST_URI, buf->data));
     }
 
+    /* Record snapshot information in metadata for checkpoint. */
+    if (txn->snapshot_count > 0) {
+        WT_ERR(__wt_buf_fmt(session, buf,
+          WT_SYSTEM_CKPT_SNAPSHOT_MIN "=%" PRIu64 "," WT_SYSTEM_CKPT_SNAPSHOT_MAX "=%" PRIu64
+                                      "," WT_SYSTEM_CKPT_SNAPSHOT_COUNT "=%" PRIu32
+                                      "," WT_SYSTEM_CKPT_SNAPSHOT "=[",
+          txn->snap_min, txn->snap_max, txn->snapshot_count));
+
+        for (snap_count = 0; snap_count < txn->snapshot_count - 1; ++snap_count)
+            WT_ERR(__wt_buf_catfmt(session, buf, "%" PRIu64 "%s", txn->snapshot[snap_count], ","));
+
+        WT_ERR(__wt_buf_catfmt(session, buf, "%" PRIu64 "%s", txn->snapshot[snap_count], "]"));
+        WT_ERR(__wt_metadata_update(session, WT_SYSTEM_CKPT_SNAPSHOT_URI, buf->data));
+    }
+
     /* Record the base write gen in metadata as part of checkpoint */
     WT_ERR(__wt_buf_fmt(
       session, buf, WT_SYSTEM_BASE_WRITE_GEN "=%" PRIu64, S2C(session)->base_write_gen));
diff --git a/src/third_party/wiredtiger/src/txn/txn_recover.c b/src/third_party/wiredtiger/src/txn/txn_recover.c
index a4bca612341..044a3b00f02 100644
--- a/src/third_party/wiredtiger/src/txn/txn_recover.c
+++ b/src/third_party/wiredtiger/src/txn/txn_recover.c
@@ -453,6 +453,70 @@ __recovery_set_oldest_timestamp(WT_RECOVERY *r)
 }
 
 /*
+ * __recovery_set_checkpoint_snapshot --
+ *     Set the checkpoint snapshot details as retrieved from the metadata file.
+ */
+static int
+__recovery_set_checkpoint_snapshot(WT_SESSION_IMPL *session)
+{
+    WT_CONFIG list;
+    WT_CONFIG_ITEM cval;
+    WT_CONFIG_ITEM k;
+    WT_CONNECTION_IMPL *conn;
+    WT_DECL_RET;
+    uint8_t counter;
+    char *sys_config;
+
+    sys_config = NULL;
+    conn = S2C(session);
+    counter = 0;
+
+    /*
+     * Read the system checkpoint information from the metadata file and save the snapshot related
+     * details of the last checkpoint for later query. This gets saved in the connection.
+     */
+    WT_ERR_NOTFOUND_OK(
+      __wt_metadata_search(session, WT_SYSTEM_CKPT_SNAPSHOT_URI, &sys_config), false);
+    if (sys_config != NULL) {
+        WT_CLEAR(cval);
+        if (__wt_config_getones(session, sys_config, WT_SYSTEM_CKPT_SNAPSHOT_MIN, &cval) == 0 &&
+          cval.len != 0)
+            conn->recovery_ckpt_snap_min = (uint64_t)cval.val;
+
+        if (__wt_config_getones(session, sys_config, WT_SYSTEM_CKPT_SNAPSHOT_MAX, &cval) == 0 &&
+          cval.len != 0)
+            conn->recovery_ckpt_snap_max = (uint64_t)cval.val;
+
+        if (__wt_config_getones(session, sys_config, WT_SYSTEM_CKPT_SNAPSHOT_COUNT, &cval) == 0 &&
+          cval.len != 0)
+            conn->recovery_ckpt_snapshot_count = (uint32_t)cval.val;
+
+        if (__wt_config_getones(session, sys_config, WT_SYSTEM_CKPT_SNAPSHOT, &cval) == 0 &&
+          cval.len != 0) {
+            __wt_config_subinit(session, &list, &cval);
+            WT_ERR(__wt_calloc_def(
+              session, conn->recovery_ckpt_snapshot_count, &conn->recovery_ckpt_snapshot));
+            while (__wt_config_subget_next(&list, &k) == 0)
+                conn->recovery_ckpt_snapshot[counter++] = (uint64_t)k.val;
+        }
+
+        /*
+         * Make sure that checkpoint snapshot does not have any unexpected value. The recovered
+         * snapshot array should contain the values between recovered snapshot min and recovered
+         * snapshot max.
+         */
+        WT_ASSERT(session,
+          conn->recovery_ckpt_snapshot_count == counter &&
+            conn->recovery_ckpt_snapshot[0] == conn->recovery_ckpt_snap_min &&
+            conn->recovery_ckpt_snapshot[counter - 1] < conn->recovery_ckpt_snap_max);
+    }
+
+err:
+    __wt_free(session, sys_config);
+    return (ret);
+}
+
+/*
  * __recovery_set_ckpt_base_write_gen --
  *     Set the base write gen as retrieved from the metadata file.
  */
@@ -696,6 +760,7 @@ __wt_txn_recover(WT_SESSION_IMPL *session, const char *cfg[])
 
     F_SET(conn, WT_CONN_RECOVERING);
     WT_ERR(__recovery_set_ckpt_base_write_gen(&r));
+    WT_ERR(__recovery_set_checkpoint_snapshot(session));
     WT_ERR(__wt_metadata_search(session, WT_METAFILE_URI, &config));
     WT_ERR(__recovery_setup_file(&r, WT_METAFILE_URI, config));
     WT_ERR(__wt_metadata_cursor_open(session, NULL, &metac));
diff --git a/src/third_party/wiredtiger/test/csuite/random_directio/main.c b/src/third_party/wiredtiger/test/csuite/random_directio/main.c
index 2212befaadb..d887ce50337 100644
--- a/src/third_party/wiredtiger/test/csuite/random_directio/main.c
+++ b/src/third_party/wiredtiger/test/csuite/random_directio/main.c
@@ -800,7 +800,6 @@ check_db(uint32_t nth, uint32_t datasize, pid_t pid, bool directio, uint32_t fla
     char checkdir[4096], dbgdir[4096], savedir[4096];
     char *gotkey, *gotvalue, *keybuf, *p;
     char **large_arr;
-    bool fatal;
 
     keybuf = dcalloc(datasize, 1);
     lastid = dcalloc(nth, sizeof(uint64_t));
@@ -825,21 +824,9 @@ check_db(uint32_t nth, uint32_t datasize, pid_t pid, bool directio, uint32_t fla
      * Copy the original home directory explicitly without direct I/O. Copy this first because
      * copying with directio may abort and we want to see what the original copy saw.
      */
-    fatal = copy_directory(home, dbgdir, false);
-    if (fatal) {
-        printf("FATAL: Copying from %s to %s, directio %d\n", home, dbgdir, false);
-        kill_child(pid);
-    }
-    fatal = copy_directory(home, checkdir, directio);
-    if (fatal) {
-        printf("FATAL: Copying from %s to %s, directio %d\n", home, checkdir, directio);
-        kill_child(pid);
-    }
-    fatal = copy_directory(checkdir, savedir, false);
-    if (fatal) {
-        printf("FATAL: Copying from %s to %s, directio %d\n", checkdir, savedir, false);
-        kill_child(pid);
-    }
+    copy_directory(home, dbgdir, false);
+    copy_directory(home, checkdir, directio);
+    copy_directory(checkdir, savedir, false);
 
     printf("Open database, run recovery and verify content\n");
     ret = wiredtiger_open(checkdir, NULL, ENV_CONFIG_REC, &conn);
diff --git a/src/third_party/wiredtiger/test/csuite/random_directio/util.c b/src/third_party/wiredtiger/test/csuite/random_directio/util.c
index df8b65ce248..a69dfd28ba1 100644
--- a/src/third_party/wiredtiger/test/csuite/random_directio/util.c
+++ b/src/third_party/wiredtiger/test/csuite/random_directio/util.c
@@ -43,7 +43,7 @@
  * copy_directory --
  *     Copy a directory, using direct IO if indicated.
  */
-bool
+void
 copy_directory(const char *fromdir, const char *todir, bool directio)
 {
     struct dirent *dp;
@@ -52,10 +52,9 @@ copy_directory(const char *fromdir, const char *todir, bool directio)
     size_t blksize, bufsize, readbytes, n, remaining;
     ssize_t ioret;
     uintptr_t bufptr;
-    int enoent, openflags, rfd, wfd;
+    int openflags, rfd, wfd;
     u_char *buf, *orig_buf;
     char fromfile[4096], tofile[4096];
-    bool fatal;
 
 #ifdef O_DIRECT
     openflags = directio ? O_DIRECT : 0;
@@ -66,8 +65,6 @@ copy_directory(const char *fromdir, const char *todir, bool directio)
     orig_buf = dcalloc(COPY_BUF_SIZE, sizeof(u_char));
     buf = NULL;
     blksize = bufsize = 0;
-    enoent = 0;
-    fatal = false;
 
     dirp = opendir(todir);
     if (dirp != NULL) {
@@ -105,16 +102,7 @@ copy_directory(const char *fromdir, const char *todir, bool directio)
          * directory will still return its entry. Handle that case and skip the file if it happens.
          */
         if (rfd < 0 && errno == ENOENT) {
-            ++enoent;
-            /*
-             * At most there can be one thread in the middle of drop due to the schema lock. So if
-             * we find more than one missing file, we have a fatal and unexpected situation. We want
-             * to know all the files in this. So note them here and fail later.
-             */
-            printf("COPY_DIR: direct:%d ENOENT %d: Source file %s not found.\n", directio, enoent,
-              dp->d_name);
-            if (enoent > 1)
-                fatal = true;
+            printf("COPY_DIR: direct:%d ENOENT Source file %s not found.\n", directio, dp->d_name);
             continue;
         }
         testutil_assertfmt(rfd >= 0, "Open of source %s failed with %d\n", fromfile, errno);
@@ -166,5 +154,4 @@ copy_directory(const char *fromdir, const char *todir, bool directio)
     }
     testutil_check(closedir(dirp));
     free(orig_buf);
-    return (fatal);
 }
diff --git a/src/third_party/wiredtiger/test/csuite/random_directio/util.h b/src/third_party/wiredtiger/test/csuite/random_directio/util.h
index a849150d52c..57ed381a112 100644
--- a/src/third_party/wiredtiger/test/csuite/random_directio/util.h
+++ b/src/third_party/wiredtiger/test/csuite/random_directio/util.h
@@ -30,4 +30,4 @@
  * util.h
  * 	Utility functions for test that simulates system crashes.
  */
-extern bool copy_directory(const char *, const char *, bool);
+extern void copy_directory(const char *, const char *, bool);
diff --git a/src/third_party/wiredtiger/test/evergreen.yml b/src/third_party/wiredtiger/test/evergreen.yml
index 6da3fa56e90..2dd16239845 100755
--- a/src/third_party/wiredtiger/test/evergreen.yml
+++ b/src/third_party/wiredtiger/test/evergreen.yml
@@ -2351,7 +2351,6 @@ tasks:
     tags: ["stress-test-3", "stress-test-zseries-3"]
 
   - name: cyclomatic-complexity
-    tags: ["pull_request"]
     commands:
       - func: "get project"
       - command: shell.exec
@@ -2395,7 +2394,6 @@ buildvariants:
     - name: make-check-asan-test
     - name: configure-combinations
     - name: checkpoint-filetypes-test
-    - name: coverage-report
     - name: unit-test-long
     - name: spinlock-gcc-test
     - name: spinlock-pthread-adaptive-test
@@ -2405,7 +2403,6 @@ buildvariants:
     - name: long-test
     - name: static-wt-build-test
     - name: format-failure-configs-test
-    - name: cyclomatic-complexity
 
 - name: ubuntu1804-compilers
   display_name: "! Ubuntu 18.04 Compilers"
@@ -2508,7 +2505,6 @@ buildvariants:
     - name: ftruncate-test
     - name: long-test
     - name: configure-combinations
-    - name: coverage-report
 
 - name: large-scale-tests
   display_name: "~ Large scale tests"
@@ -2518,6 +2514,17 @@ buildvariants:
   tasks:
     - name: million-collection-test
 
+- name: code-statistics
+  display_name: "Code statistics"
+  batchtime: 1440 # 1 day
+  run_on:
+  - ubuntu1804-test
+  expansions:
+    test_env_vars: LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libeatmydata.so PATH=/opt/mongodbtoolchain/v3/bin:$PATH LD_LIBRARY_PATH=$(pwd)/.libs top_srcdir=$(pwd)/.. top_builddir=$(pwd)
+  tasks:
+    - name: coverage-report
+    - name: cyclomatic-complexity
+
 - name: compatibility-tests-less-frequent
   display_name: Compatibility tests (less frequent)
   batchtime: 10080 # 7 days
diff --git a/src/third_party/wiredtiger/test/suite/test_checkpoint_snapshot01.py b/src/third_party/wiredtiger/test/suite/test_checkpoint_snapshot01.py
new file mode 100644
index 00000000000..a6eb0cf4905
--- /dev/null
+++ b/src/third_party/wiredtiger/test/suite/test_checkpoint_snapshot01.py
@@ -0,0 +1,83 @@
+#!/usr/bin/env python
+#
+# Public Domain 2014-2020 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.
+
+from helper import copy_wiredtiger_home
+import wiredtiger, wttest
+from wtdataset import SimpleDataSet
+from wtscenario import make_scenarios
+from wiredtiger import stat
+
+# test_checkpoint_snapshot01.py
+#   Checkpoint snapshot - Create multiple sessions which creates snapshots and
+#   checkpoint to save the snapshot details in metadata file.
+#
+
+class test_checkpoint_snapshot01(wttest.WiredTigerTestCase):
+    conn_config = 'cache_size=50MB,statistics=(fast)'
+
+    # Create a table.
+    uri = "table:test_checkpoint_snapshot01"
+
+    nsessions = 5
+    nkeys = 40
+    nrows = 100
+
+    def test_checkpoint_snapshot(self):
+
+        ds = SimpleDataSet(self, self.uri, self.nrows, key_format="S", value_format='u')
+        ds.populate()
+        value = b"aaaaa" * 100
+
+        sessions = [0] * self.nsessions
+        cursors = [0] * self.nsessions
+
+        for j in range (0, self.nsessions):
+            sessions[j] = self.conn.open_session()
+            cursors[j] = sessions[j].open_cursor(self.uri)
+            sessions[j].begin_transaction('isolation=snapshot')
+
+            start = (j * self.nkeys)
+            end = start + self.nkeys
+
+            for i in range(start, end):
+                cursors[j].set_key(ds.key(self.nrows + i))
+                cursors[j].set_value(value)
+                self.assertEquals(cursors[j].insert(),0)
+
+        session_p2 = self.conn.open_session()
+        session_p2.checkpoint()
+
+        #Simulate a crash by copying to a new directory(RESTART).
+        copy_wiredtiger_home(".", "RESTART")
+
+        # Open the new directory.
+        self.conn = self.setUpConnectionOpen("RESTART")
+        self.session = self.setUpSessionOpen(self.conn)
+
+if __name__ == '__main__':
+    wttest.run()