[CAMEL-16734] Recipient list does not wait for processing an exchange by recipients and ignores aggregation strategy when route is transacted.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.7.4, 3.7.2, 3.7.3, 3.8.0, 3.10.0
• Fix Version/s: 3.11.0
• Component/s: camel-core
• Estimated Complexity: Unknown
• Assignee: Claus Ibsen
• Reporter: Krzysztof Mackowiak
• Created: 18/Jun/21 15:06
• Updated: 21/Jun/21 14:40
• Resolved: 21/Jun/21 06:07

Description

When migrating to Camel 3.7.2 I've noticed that there is a problem with the recipient list in transacted routes.
Recipient list does not wait for processing an exchange by recipients and ignores aggregation strategy when :

• route is transacted,
• doTry()...doCatch() is used,
• processing by the recipient takes longer.

The bug was discovered in version 3.7.2 but it's also present in the newest versions 3.10.0 and 3.7.4 (LTS).

Here is a test, which reproduces the problem:

public class TransactedRecipientListTest extends TransactionClientDataSourceSupport {

    @Test
    public void testRecipientList() throws Exception {
        System.out.println("Running on version : " + context.getVersion());

        String response = template.requestBody("direct:start", "Hello World", String.class);

        assertEquals("Hi !!!", response);
    }

    @Override
    protected RouteBuilder createRouteBuilder() throws Exception {
        return new RouteBuilder() {
            @Override
            public void configure() throws Exception {
                // NOTE commenting transacted(), doTry() or delay() make this test green in Camel 3.7.4 and above
                // however commenting delay() doest not make this test green in Camel 3.7.2
                from("direct:start")
                        .transacted()
                        .doTry()
                            .recipientList(constant("direct:a"))
                        .endDoTry();
                // NOTE doCatch() skipped here to keep test as simple as possible

                from("direct:a")
                        .delay(1000)
                        .transform(constant("Hi !!!"));
            }
        };
    }
}

This test is passing with Camel 3.7.1 and below, but it's failing with Camel 3.7.2 and above.
However it's also passing with Camel 3.9.0 !

It's also passing on 'main' and '3.7.x' branches after reverting commit b1b5b7d0 : "CAMEL-16550: camel-core - Split and Aggregate with Transacted may cause thread to stuck".

I've checked a history of MulticastProcessor class and it looks that:

• CAMEL-16103 introduced the problem.
• CAMEL-16295 fixed the problem.
• CAMEL-16550 introduced this problem again.

Issue Links

• relates to: CAMEL-16737 camel-core - Transacted vs reactive routing engine