Fix memory leak at outbox email queueing (#66)

daniel-lerch · Jun 10, 2024 · d672900 · d672900
1 parent 87b14fa
commit d672900
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Showing 3 changed files with 20 additions and 11 deletions.
diff --git a/server/Korga/EmailDelivery/EmailDeliveryJobController.cs b/server/Korga/EmailDelivery/EmailDeliveryJobController.cs
@@ -38,10 +38,8 @@ protected override async ValueTask ExecuteJob(OutboxEmail outboxEmail, Cancellat
     {
         SmtpClient smtp = await GetConnection(cancellationToken);
 
-        MimeMessage mimeMessage;
-
-        using (MemoryStream memoryStream = new(outboxEmail.Content))
-            mimeMessage = MimeMessage.Load(memoryStream, CancellationToken.None);
+        using MemoryStream memoryStream = new(outboxEmail.Content);
+        using MimeMessage mimeMessage = MimeMessage.Load(memoryStream, CancellationToken.None);
 
         try
         {

diff --git a/server/Korga/EmailDelivery/EmailDeliveryService.cs b/server/Korga/EmailDelivery/EmailDeliveryService.cs
@@ -1,4 +1,5 @@
-using Korga.Utilities;
+using Korga.EmailDelivery.Entities;
+using Korga.Utilities;
 using Microsoft.EntityFrameworkCore;
 using MimeKit;
 using System;
@@ -35,8 +36,14 @@ public async ValueTask<bool> Enqueue(string emailAddress, MimeMessage mimeMessag
             content = memoryStream.ToArray();
         }
 
-        database.OutboxEmails.Add(new(emailAddress, content) { InboxEmailId = inboxEmailId });
+        OutboxEmail outboxEmail = new(emailAddress, content) { InboxEmailId = inboxEmailId };
+        database.OutboxEmails.Add(outboxEmail);
         await database.SaveChangesAsync(cancellationToken);
+
+        // Explicitly free entity for garbage collection because our DbContext won't be disposed soon enough
+        // Without this line, Korga takes gigabytes of memory when sending large messages to many recipients
+        database.Entry(outboxEmail).State = EntityState.Detached;
+
         jobQueue.EnsureRunning();
         return true;
     }

diff --git a/server/Korga/EmailRelay/EmailRelayJobController.cs b/server/Korga/EmailRelay/EmailRelayJobController.cs
@@ -40,7 +40,8 @@ protected override async ValueTask ExecuteJob(InboxEmail email, CancellationToke
     {
         if (email.Receiver == null)
         {
-            await SendErrorMessage(email, emailRelay.InvalidServerConfiguration(email), cancellationToken);
+            using MimeMessage? errorMessage = emailRelay.InvalidServerConfiguration(email);
+            await SendErrorMessage(email, errorMessage, cancellationToken);
 
             logger.LogWarning("Could not determine receiver for message #{Id} from {From} to {To}. This message will not be forwarded." +
                 "Please make sure your email provider specifies the receiver in the Received, Envelope-To, or X-Envelope-To header", email.Id, email.From, email.To);
@@ -54,23 +55,26 @@ protected override async ValueTask ExecuteJob(InboxEmail email, CancellationToke
 
         if (distributionList == null)
         {
-            await SendErrorMessage(email, emailRelay.InvalidAlias(email), cancellationToken);
+            using MimeMessage? errorMessage = emailRelay.InvalidAlias(email);
+            await SendErrorMessage(email, errorMessage, cancellationToken);
 
             logger.LogInformation("No group found with alias {Receiver} for email #{Id} from {From}", email.Receiver, email.Id, email.From);
             return;
         }
 
         if (email.Header == null)
         {
-            await SendErrorMessage(email, emailRelay.TooManyHeaders(email), cancellationToken);
+            using MimeMessage? errorMessage = emailRelay.TooManyHeaders(email);
+            await SendErrorMessage(email, errorMessage, cancellationToken);
 
             logger.LogInformation("Email #{Id} from {From} to {Receiver} exceeded the header size limit", email.Id, email.From, email.Receiver);
             return;
         }
 
         if (email.Body == null)
         {
-            await SendErrorMessage(email, emailRelay.TooBigMessage(email), cancellationToken);
+            using MimeMessage? errorMessage = emailRelay.TooBigMessage(email);
+            await SendErrorMessage(email, errorMessage, cancellationToken);
 
             logger.LogInformation("Email #{Id} from {From} to {Receiver} exceeded the body size limit", email.Id, email.From, email.Receiver);
             return;
@@ -79,7 +83,7 @@ protected override async ValueTask ExecuteJob(InboxEmail email, CancellationToke
         MailboxAddress[] recipients = await distributionListService.GetRecipients(distributionList, cancellationToken);
         foreach (MailboxAddress address in recipients)
         {
-            MimeMessage preparedMessage = distributionList.Flags.HasFlag(DistributionListFlags.Newsletter)
+            using MimeMessage preparedMessage = distributionList.Flags.HasFlag(DistributionListFlags.Newsletter)
                 ? await emailRelay.PrepareForForwardTo(email, address, cancellationToken)
                 : emailRelay.PrepareForResentTo(email, address);
             await emailDelivery.Enqueue(address.Address, preparedMessage, email.Id, cancellationToken);