diff --git a/HISTORY b/HISTORY
index d9f91bd..f8fa1e1 100644
--- a/HISTORY
+++ b/HISTORY
@@ -1,5 +1,5 @@
 
-Version 1.44  2020-04-22
+Version 1.44  2020-04-24
   * add test file src/tests/test_pthread_lock.c
   * add uniq_skiplist.[hc]
   * add function split_string_ex
diff --git a/src/tests/Makefile b/src/tests/Makefile
index 6e6adc3..5603b50 100644
--- a/src/tests/Makefile
+++ b/src/tests/Makefile
@@ -8,7 +8,7 @@ ALL_PRGS = test_allocator test_skiplist test_multi_skiplist test_mblock test_blo
            test_id_generator test_ini_parser test_char_convert test_char_convert_loader \
            test_logger test_skiplist_set test_crc32 test_thourands_seperator test_sched_thread \
            test_json_parser test_pthread_lock test_uniq_skiplist test_split_string \
-           test_server_id_func test_pipe test_atomic
+           test_server_id_func test_pipe test_atomic test_file_write_hole
 
 all: $(ALL_PRGS)
 .c:
diff --git a/src/tests/test_file_write_hole.c b/src/tests/test_file_write_hole.c
new file mode 100644
index 0000000..0c508a3
--- /dev/null
+++ b/src/tests/test_file_write_hole.c
@@ -0,0 +1,83 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include <time.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <sys/time.h>
+#include "fastcommon/logger.h"
+#include "fastcommon/shared_func.h"
+
+int main(int argc, char *argv[])
+{
+#define SEEK_POS   (2 * 1024)
+    char *filename;
+    int fd;
+    int result;
+    int n;
+    char buf[1024];
+
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s <filename>\n", argv[0]);
+        return 1;
+    }
+
+    log_init();
+    filename = argv[1];
+    if (access(filename, F_OK) == 0) {
+        logError("file: "__FILE__", line: %d, "
+            "file %s already exists", __LINE__, filename);
+        return EEXIST;
+    }
+
+    fd = open(filename, O_RDWR | O_CREAT | O_TRUNC, 0644);
+    if (fd < 0) {
+        result = errno != 0 ? errno : EIO;
+        logError("file: "__FILE__", line: %d, " \
+            "open file %s fail, " \
+            "errno: %d, error info: %s", \
+            __LINE__, filename, \
+            result, STRERROR(result));
+        return result;
+    }
+
+    if (lseek(fd, SEEK_POS, SEEK_SET) < 0) {
+        logError("file: "__FILE__", line: %d, " \
+            "lseek file %s fail, " \
+            "errno: %d, error info: %s", __LINE__, \
+            filename, errno, STRERROR(errno));
+        return errno != 0 ? errno : EIO;
+    }
+
+    memset(buf, '\n', sizeof(buf));
+    if ((n=write(fd, buf, sizeof(buf))) <= 0) {
+        logError("file: "__FILE__", line: %d, " \
+            "write to file %s fail, " \
+            "errno: %d, error info: %s", __LINE__, \
+            filename, errno, STRERROR(errno));
+        return errno != 0 ? errno : EIO;
+    }
+    printf("write bytes: %d\n", n);
+
+    if (lseek(fd, 0, SEEK_SET) < 0) {
+        logError("file: "__FILE__", line: %d, " \
+            "lseek file %s fail, " \
+            "errno: %d, error info: %s", __LINE__, \
+            filename, errno, STRERROR(errno));
+        return errno != 0 ? errno : EIO;
+    }
+
+    if ((n=read(fd, buf, sizeof(buf))) <= 0) {
+        logError("file: "__FILE__", line: %d, " \
+            "read from file %s fail, " \
+            "errno: %d, error info: %s", __LINE__, \
+            filename, errno, STRERROR(errno));
+        return errno != 0 ? errno : EIO;
+    }
+
+    printf("read bytes: %d, 0 => 0x%02x, %d => 0x%02x\n",
+            n, (unsigned char)buf[0], n - 1, (unsigned char)buf[n - 1]);
+    return 0;
+}
diff --git a/src/uniq_skiplist.h b/src/uniq_skiplist.h
index 83550ad..35980d9 100644
--- a/src/uniq_skiplist.h
+++ b/src/uniq_skiplist.h
@@ -157,6 +157,9 @@ static inline bool uniq_skiplist_empty(UniqSkiplist *sl)
 #define LEVEL0_DOUBLE_CHAIN_PREV_LINK(node)  node->links[node->level_index + 1]
 #define LEVEL0_DOUBLE_CHAIN_TAIL(sl)  LEVEL0_DOUBLE_CHAIN_PREV_LINK(sl->top)
 
+#define UNIQ_SKIPLIST_LEVEL0_TAIL_NODE(sl)    ((UniqSkiplistNode *) \
+        LEVEL0_DOUBLE_CHAIN_TAIL(sl))
+
 #define UNIQ_SKIPLIST_LEVEL0_PREV_NODE(node)  ((UniqSkiplistNode *) \
         LEVEL0_DOUBLE_CHAIN_PREV_LINK(node))