From 0f4cded8cec21924037e39fd1b6fde30ba6f353b Mon Sep 17 00:00:00 2001
From: Seonpyo Kim <spkim@kodebox.io>
Date: Thu, 30 May 2019 18:12:16 +0900
Subject: [PATCH] Make the sync module release memory aggressively

Shrink HashMaps and Vectors of downloaders and Verification queue
to reduce the memory usage when syncing.
---
 core/src/verification/queue/mod.rs  | 2 ++
 sync/src/block/downloader/body.rs   | 7 +++++++
 sync/src/block/downloader/header.rs | 2 ++
 3 files changed, 11 insertions(+)

diff --git a/core/src/verification/queue/mod.rs b/core/src/verification/queue/mod.rs
index b089a4c3be..2521d41820 100644
--- a/core/src/verification/queue/mod.rs
+++ b/core/src/verification/queue/mod.rs
@@ -408,6 +408,7 @@ impl<K: Kind> VerificationQueue<K> {
                 *td -= score;
             }
         }
+        processing.shrink_to_fit();
         processing.is_empty()
     }
 
@@ -444,6 +445,7 @@ impl<K: Kind> VerificationQueue<K> {
                 new_verified.push_back(output);
             }
         }
+        processing.shrink_to_fit();
 
         self.verification.sizes.verified.fetch_sub(removed_size, AtomicOrdering::SeqCst);
         *verified = new_verified;
diff --git a/sync/src/block/downloader/body.rs b/sync/src/block/downloader/body.rs
index af3fd86581..e9c1885f76 100644
--- a/sync/src/block/downloader/body.rs
+++ b/sync/src/block/downloader/body.rs
@@ -69,6 +69,7 @@ impl BodyDownloader {
                 self.downloaded.insert(hash, body);
             }
         }
+        self.downloading.shrink_to_fit();
     }
 
     pub fn add_target(&mut self, header: &Header, parent: &Header) {
@@ -93,6 +94,9 @@ impl BodyDownloader {
             self.downloading.remove(hash);
             self.downloaded.remove(hash);
         }
+        self.targets.shrink_to_fit();
+        self.downloading.shrink_to_fit();
+        self.downloaded.shrink_to_fit();
     }
 
     pub fn reset_downloading(&mut self, hashes: &[H256]) {
@@ -100,6 +104,7 @@ impl BodyDownloader {
         for hash in hashes {
             self.downloading.remove(&hash);
         }
+        self.downloading.shrink_to_fit();
     }
 
     pub fn drain(&mut self) -> Vec<(H256, Vec<UnverifiedTransaction>)> {
@@ -111,7 +116,9 @@ impl BodyDownloader {
                 break
             }
         }
+        self.downloaded.shrink_to_fit();
         self.targets.drain(0..result.len());
+        self.targets.shrink_to_fit();
         result
     }
 }
diff --git a/sync/src/block/downloader/header.rs b/sync/src/block/downloader/header.rs
index 76f88a02f0..dc6d653572 100644
--- a/sync/src/block/downloader/header.rs
+++ b/sync/src/block/downloader/header.rs
@@ -187,6 +187,7 @@ impl HeaderDownloader {
                 }
             }
         }
+        self.queued.shrink_to_fit();
     }
 
     pub fn mark_as_queued(&mut self, hashes: Vec<H256>) {
@@ -195,5 +196,6 @@ impl HeaderDownloader {
                 self.queued.insert(hash, header);
             }
         }
+        self.downloaded.shrink_to_fit();
     }
 }