(poi-xmlbeans) branch trunk updated: Close the javac pipes and join the drain threads in externalCompile (#110)

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pjfanning pushed a commit to branch trunk
in repository https://gitbox.apache.org/repos/asf/poi-xmlbeans.git


The following commit(s) were added to refs/heads/trunk by this push:
     new 9d129236 Close the javac pipes and join the drain threads in externalCompile (#110)
9d129236 is described below

commit 9d129236e775789225df9556ca31aa4129f21013
Author: PJ Fanning <pj...@users.noreply.github.com>
AuthorDate: Mon Sep 7 12:57:17 2026 +0100

    Close the javac pipes and join the drain threads in externalCompile (#110)
    
    CodeGenUtil.externalCompile never closed any of the three pipes it opened for
    the compiler process. proc.getOutputStream() (stdin, which javac never reads)
    was left open, and the BufferedReaders wrapping stdout and stderr in copy()
    were never closed, so three file descriptors per invocation were held until
    the Process was collected.
    
    The drain threads were also never joined: proc.waitFor() returns as soon as
    the process exits, which can be before the readers have finished appending, so
    the compiler diagnostics printed just below could be truncated or empty. The
    "out" and "err" locals were assigned and then unused.
    
    Close stdin up front, join both readers after waitFor(), destroy the process in
    a finally, and let copy() close its reader when the pipe is drained.
    
    Co-authored-by: Claude Opus 5 (1M context) <no...@anthropic.com>
---
 .../org/apache/xmlbeans/impl/tool/CodeGenUtil.java | 31 +++++++++++++++++-----
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/src/main/java/org/apache/xmlbeans/impl/tool/CodeGenUtil.java b/src/main/java/org/apache/xmlbeans/impl/tool/CodeGenUtil.java
index c3db6e08..80c2264b 100644
--- a/src/main/java/org/apache/xmlbeans/impl/tool/CodeGenUtil.java
+++ b/src/main/java/org/apache/xmlbeans/impl/tool/CodeGenUtil.java
@@ -242,10 +242,23 @@ public class CodeGenUtil {
             StringBuilder errorBuffer = new StringBuilder();
             StringBuilder outputBuffer = new StringBuilder();
 
-            Thread out = copy(proc.getInputStream(), outputBuffer);
-            Thread err = copy(proc.getErrorStream(), errorBuffer);
-
-            proc.waitFor();
+            try {
+                // the compiler reads nothing from stdin - leaving the pipe open just
+                // holds a file descriptor until the Process is collected
+                proc.getOutputStream().close();
+
+                Thread out = copy(proc.getInputStream(), outputBuffer);
+                Thread err = copy(proc.getErrorStream(), errorBuffer);
+
+                proc.waitFor();
+
+                // the readers can still be draining the pipes after the process exits,
+                // so join before reporting what they collected
+                out.join();
+                err.join();
+            } finally {
+                proc.destroy();
+            }
 
             if (verbose || proc.exitValue() != 0) {
                 if (outputBuffer.length() > 0) {
@@ -347,9 +360,13 @@ public class CodeGenUtil {
      */
     private static Thread copy(InputStream stream, final StringBuilder output) {
         final BufferedReader reader = new BufferedReader(new InputStreamReader(stream, Charset.defaultCharset()));
-        Thread readerThread = new Thread(() ->
-            reader.lines().forEach(s -> output.append(s).append('\n'))
-        );
+        Thread readerThread = new Thread(() -> {
+            try (BufferedReader r = reader) {
+                r.lines().forEach(s -> output.append(s).append('\n'));
+            } catch (IOException e) {
+                // nothing useful to do with a failure to drain the pipe
+            }
+        });
         readerThread.start();
         return readerThread;
     }


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