[CAMEL-14579] Camel-mail: MemoryLeak when sending mails using recipient list or dynamic to

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.0.1
• Fix Version/s: 3.1.0
• Component/s: camel-mail
• Estimated Complexity: Unknown
• Regression: Regression
• Assignee: Claus Ibsen
• Reporter: Pascal Schumacher
• Created: 17/Feb/20 08:50
• Updated: 21/Feb/20 06:55
• Resolved: 20/Feb/20 05:14

Description

In Camel 3.0.1 there seems to be a memory leak when you use camel-mail to send mails with a recipient list (see attached screenshot CamelMail_RecipientList_MemoryLeak_3.0.1.PNG).

Code to reproduce:

public class SendMailDynamicToMemoryLeakTest extends CamelTestSupport {

    @Override
    protected RouteBuilder createRouteBuilder() {
        return new RouteBuilder() {
            public void configure() {
                from("scheduler:start?delay=1")
                    .setBody(constant("Hello"))
                    .setHeader("smtpFrom", method(UUID.class, "randomUUID"))
                    .recipientList(simple("smtp://localhost:1234?to=[e-mail]&mail.smtp.from=${header.smtpFrom}")).cacheSize(-1).end();
//                    .toD("smtp://localhost:1234?to=[e-mail]&mail.smtp.from=${header.smtpFrom}");
            }
        };
    }

    @Test
    public void test() throws Exception {
        Thread.sleep(100_000_000L);
    }
}

<dependency>
    <groupId>com.bitmechanic</groupId>
    <artifactId>dumbster</artifactId>
    <version>1.9.0.2</version>
</dependency>

public class TestMailServer {

    public static void main(String[] args) throws Exception {
        ServerOptions serverOptions = new ServerOptions();
        serverOptions.port = 1234;
        SmtpServerFactory.startServer(serverOptions);
    }
}

To make reproduction easier I pushed everything to https://github.com/PascalSchumacher/CamelSendMailMemoryLeak

Run the TestMailServer class, then run SendMailDynamicToMemoryLeakTest.

Using Camel 3.1.0-SNAPSHOT to run the test shows the same behavior.

Using Camel 2.24.2 there is no memory leak.

—

The original code is using toD (see commented out code in the test case above) instead of a recipient list. For dynamic to there seems to be a slower memory leak in Camel 3.0.1 (not completely sure, a lot of objects get garbage collected, but overall object count seems to slowly increase.)

Using Camel 2.24.2 there is no memory leak.

Using Camel 3.1.0-SNAPSHOT with dynamic to there seems to be a memory leak, see the attached screenshot CamelMail_DyamicTo_MemoryLeak-3.1.0-SNAPSHOT.PNG.

I am not sure if the recipientList/toD behavior is limited to camel-mail or if it would occur for other components too. I could not replicate the behavior with camel-http, but this component uses optimized dynamic to and this may prevent the occurrence of a memory leak.

Issue Links

• is related to: CAMEL-14594 ProducerServicePool - Memory leak
• relates to: CAMEL-14591 Recipient List EIP - MemoryLeak
• relates to: CAMEL-14586 camel-core - Disable cache on some EIPs seems to not be working correlction
• relates to: CAMEL-14595 camel-mail - Allow to use headers for additional mail properties