diff --git a/azkaban-common/src/main/java/azkaban/project/JdbcProjectLoader.java b/azkaban-common/src/main/java/azkaban/project/JdbcProjectLoader.java
index 61a96af..f9b1fbd 100644
--- a/azkaban-common/src/main/java/azkaban/project/JdbcProjectLoader.java
+++ b/azkaban-common/src/main/java/azkaban/project/JdbcProjectLoader.java
@@ -387,10 +387,12 @@ public class JdbcProjectLoader extends AbstractJdbcLoader implements
* Insert a new version record to TABLE project_versions before uploading files.
*
* The reason for this operation:
- * When error chunking happens in remote mysql server, incomplete file data is remained
+ * When error chunking happens in remote mysql server, incomplete file data remains
* in DB, and an SQL exception is thrown. If we don't have this operation before uploading file,
* the SQL exception prevents AZ from creating the new version record in Table project_versions.
- * However, the Table project_files still reserve the incomplete files, which causes version inconsistency.
+ * However, the Table project_files still reserve the incomplete files, which causes troubles
+ * when uploading a new file: Since the version in TABLE project_versions is still old, mysql will stop
+ * inserting new files to db.
*
* Why this operation is safe:
* When AZ uploads a new zip file, it always fetches the latest version proj_v from TABLE project_version,
@@ -404,6 +406,11 @@ public class JdbcProjectLoader extends AbstractJdbcLoader implements
"INSERT INTO project_versions (project_id, version, upload_time, uploader, file_type, file_name, md5, num_chunks) values (?,?,?,?,?,?,?,?)";
try {
+
+ /**
+ * As we don't know the num_chunks before uploading the file, we initialize it to 0,
+ * and will update it after uploading completes.
+ */
runner.update(connection, INSERT_PROJECT_VERSION, project.getId(),
version, updateTime, uploader, filetype, filename, md5, 0);
} catch (SQLException e) {
@@ -438,7 +445,7 @@ public class JdbcProjectLoader extends AbstractJdbcLoader implements
* in order to reduce the transaction duration and conserve sql server resources.
*
* If the files to be uploaded is very large and we don't commit every single chunk,
- * the remote mysql server will have troubles, e.g. memory starvation.
+ * the remote mysql server will run into memory troubles.
*/
connection.commit();
logger.info("Finished update for " + filename + " chunk " + chunk);
@@ -456,8 +463,7 @@ public class JdbcProjectLoader extends AbstractJdbcLoader implements
}
/**
- * Since num_chunks is initialized to 0 before uploading files, we update its
- * actual number to db here.
+ * we update num_chunks's actual number to db here.
*
* NOTE: When Error chunking happens, the following sql statements will be skipped.
*/
