[jira] [Commented] (CSV-295) Support for parallelism in CSVPrinter

[Gary D. Gregory (Jira)]

    [ 
https://issues.apache.org/jira/browse/CSV-295?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17504582#comment-17504582
 ] 

Gary D. Gregory commented on CSV-295:
-------------------------------------

There are 2 solutions, I'm not sure why a semaphore is needed.

(1) Lock the printer as needed with synchronized(someCsvPrinterVar) or

(2) Update Commons CSV with:

{code:java}
diff --git a/src/main/java/org/apache/commons/csv/CSVPrinter.java 
b/src/main/java/org/apache/commons/csv/CSVPrinter.java
index 171bcff..9dcb95c 100644
--- a/src/main/java/org/apache/commons/csv/CSVPrinter.java
+++ b/src/main/java/org/apache/commons/csv/CSVPrinter.java
@@ -162,7 +162,7 @@
      * @throws IOException
      *             If an I/O error occurs
      */
-    public void print(final Object value) throws IOException {
+    public synchronized void print(final Object value) throws IOException {
         format.print(value, appendable, newRecord);
         newRecord = false;
     }
@@ -188,7 +188,7 @@
      * @throws IOException
      *             If an I/O error occurs
      */
-    public void printComment(final String comment) throws IOException {
+    public synchronized void printComment(final String comment) throws 
IOException {
         if (comment == null || !format.isCommentMarkerSet()) {
             return;
         }
@@ -226,7 +226,7 @@
      * @throws SQLException If a database access error occurs or this method 
is called on a closed result set.
      * @since 1.9.0
      */
-    public void printHeaders(final ResultSet resultSet) throws IOException, 
SQLException {
+    public synchronized void printHeaders(final ResultSet resultSet) throws 
IOException, SQLException {
         printRecord((Object[]) 
format.builder().setHeader(resultSet).build().getHeader());
     }
 
@@ -236,7 +236,7 @@
      * @throws IOException
      *             If an I/O error occurs
      */
-    public void println() throws IOException {
+    public synchronized void println() throws IOException {
         format.println(appendable);
         newRecord = true;
     }
@@ -254,7 +254,7 @@
      * @throws IOException
      *             If an I/O error occurs
      */
-    public void printRecord(final Iterable<?> values) throws IOException {
+    public synchronized void printRecord(final Iterable<?> values) throws 
IOException {
         for (final Object value : values) {
             print(value);
         }
{code}
 

> Support for parallelism in CSVPrinter
> -------------------------------------
>
>                 Key: CSV-295
>                 URL: https://issues.apache.org/jira/browse/CSV-295
>             Project: Commons CSV
>          Issue Type: Improvement
>          Components: Printer
>    Affects Versions: 1.9.0
>         Environment: 
> https://zio.dev/version-1.x/overview/overview_creating_effects#blocking-synchronous-side-effects
>            Reporter: Zimo Li
>            Priority: Major
>
> I am trying to write the result of network IO to a CSV file using Scala and 
> the ZIO library. The order of the rows does not matter, so I decided to use a 
> concurrency of 8.
> Each thread calls {{{}CSVPrinter.printRecord{}}}, and this caused some rows 
> to intersect with others. Eventually, I decided to use a 
> [Semaphore|https://zio.dev/version-1.x/datatypes/concurrency/semaphore] to 
> fix it.
> A locking mechanism for {{printRecord}} can be implemented just like the 
> underlying {{FileWriter}} or {{PrintWriter}}.



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