From 01d29020dc8a994935b1ead9781a339fe02657a6 Mon Sep 17 00:00:00 2001
From: Curtis Rueden <ctrueden@wisc.edu>
Date: Thu, 11 Jul 2024 15:05:03 -0500
Subject: [PATCH] WIP: Still hangs

---
 .../org/apposed/appose/SharedMemoryTest.java  | 40 ++++++++++++++++---
 1 file changed, 35 insertions(+), 5 deletions(-)

diff --git a/src/test/java/org/apposed/appose/SharedMemoryTest.java b/src/test/java/org/apposed/appose/SharedMemoryTest.java
index b8e0c01..a94d61a 100644
--- a/src/test/java/org/apposed/appose/SharedMemoryTest.java
+++ b/src/test/java/org/apposed/appose/SharedMemoryTest.java
@@ -77,10 +77,11 @@ public void testShmCreate() {
 	}
 
 	@Test
-	public void testShmAttach() throws IOException {
+	public void testShmAttach() throws IOException, InterruptedException {
 		ProcessBuilder pb = new ProcessBuilder();
 		boolean windows = System.getProperty("os.name").startsWith("Win");
 		String pythonCommand =  windows ? "python.exe" : "python";
+		System.out.println("1");
 		Process p = new ProcessBuilder().command(pythonCommand, "-c", //
 			"from multiprocessing.shared_memory import SharedMemory;" + //
 			"from sys import stdin, stdout;" + //
@@ -94,13 +95,40 @@ public void testShmAttach() throws IOException {
 			"shm.unlink()" //
 		).start();
 
-		// Read the name of the shared memory that Python created.
-		BufferedReader in = new BufferedReader(new InputStreamReader(p.getInputStream()));
-		String[] shmInfo = in.readLine().split("|");
-		assertEquals(2, shmInfo.length);
+		System.out.println("2");
+
+		// Read output of Python program in a separate thread.
+		// Because pipes need threads to avoid clogging up.
+		String[] shmInfo = new String[2];
+		synchronized (shmInfo) {
+			Thread t = new Thread(() -> {
+				System.out.println("4");
+				// Read the name of the shared memory that Python created.
+				BufferedReader in = new BufferedReader(new InputStreamReader(p.getInputStream()));
+				try {
+					String[] tokens = in.readLine().split("|");
+					shmInfo[0] = tokens[0];
+					shmInfo[1] = tokens[1];
+				} catch (IOException exc) {
+					exc.printStackTrace();
+				}
+				System.out.println("5");
+				synchronized (shmInfo) {
+					shmInfo.notify();
+				}
+			});
+			System.out.println("3");
+			t.start();
+			shmInfo.wait();
+			System.out.println("6");
+		}
+		System.out.println("7");
+		//t.join();
 		String shmName = shmInfo[0];
+		assertNotNull(shmName);
 		int shmSize = Integer.parseInt(shmInfo[1]);
 		assertEquals(345, shmSize);
+		System.out.println("8");
 
 		// Attach to the shared memory.
 		try (SharedMemory shm = SharedMemory.attach(shmName)) {
@@ -113,10 +141,12 @@ public void testShmAttach() throws IOException {
 			assertEquals(45, buf.get(100));
 			assertEquals(67, buf.get(344));
 		}
+		System.out.println("9");
 
 		// Close out the Python process.
 		OutputStream os = p.getOutputStream();
 		os.write('\n');
 		os.flush();
+		System.out.println("10");
 	}
 }