Memory leak

[workpage2]

I am using this code to check the email parameters and the presence of an SMTP server on the network.
if (smtp.connect(&session))
{
Serial.println("OK");
}
else
{
Serial.println("Fail");
}
But after the execution of this function, the memory is not returned. If you then execute MailClient.sendMail(&smtp, &message) the memory is returned.

Free memory=194392
> C: Wait for NTP server time synching
SMTP server connected, wait for greeting...
Sending greeting response...
Logging in...
Free memory=149928

Now send email

Sending Email...
Sending message header...
Sending message body...
Finishing the message sending...
Closing the session...
Message sent successfully
----------------
Message sent success: 1
Message sent failled: 0
----------------
Message No: 1
Status: success
Date/Time: 2023/3/2 19:19:11
Recipient: [email protected]
Subject: test
----------------
Free memory=194492

I check the connection to the email server every hour. And with each check, the memory leaks. A day later, I can no longer send a letter.

[mobizt]

I don't see memory leaks from intensive test 24/7 for years and memory allocation in this library is done by well manage code.
You should debug your code first.

[workpage2]

Can I use smtp.connect(&session) without sending email? Just to check the connection?

[mobizt]

Yes, you are ready logged after calling connect.

[mobizt]

You should know that library keeps the sending log inside the SMTPSession object. You can clear it by this code that I comment it in all exmples.

ESP-Mail-Client/examples/SMTP/Send_Text/Send_Text.ino

Lines 296 to 297 in caae858

	// to clear sending result log
	// smtp.sendingResult.clear();

[workpage2]

I am using this line.
However, after calling smtp.connect(&session) the amount of memory in the heap is reduced by 50kb, and is returned only if an email is sent.

[mobizt]

I don't see this problem. Without code I can't tell what's happen in your case, but all examples are ok from intensively test.

[workpage2]

Serial.print("\nFree memory=");
Serial.println(ESP.getFreeHeap());
if (smtp.connect(&session))
{
Serial.println("OK");
}
else
{
Serial.println("Fail");
}
Serial.print("\nFree memory=");
Serial.println(ESP.getFreeHeap());

[mobizt]

I'll check and inform you if there is update.

[mobizt]

Thanks for informing this issue.

You are right, the memory leaks on TCP client initializing in ESP8266 and Raspberry Pi Pico.

Now it fixed already in v3.0.1, please update.

[workpage2]

After running smtp.connect(&session) the amount of memory is reduced by 50kb. However, if you then run MailClient.sendMail(&smtp, &message) the memory is returned.
I use smtp.connect(&session) to check SMTP availability, so I always have -50k of memory.

[workpage2]

I tested this with an example from the library.

[mobizt]

From iteration testing in loop.

The maximum heap reduced from first round running to the subsequence round is not greater than 3k.

I will post the code and result here soon.

[mobizt]

I think I know what you called memory leak.

If your device free Heap before calling connect is approx. 230k and drop to 190k after connected, it is normal as memory used by the SSL client while the session is opened.

You can call smtp.closeSession() to close it then the memory will be released like when you calling send mail that the session will be closed after sending by default.

The mbedTLS library used in this library holds approx. 50k for the SSL session.

Only memory leaks issue in ESP8266/Pico SSL clients that was already fixed.

[workpage2]

That helped. Thank you.