Use connection pools.

lib/pleroma/web/activity_pub/activity_pub.ex

@@ -351,7 +351,7 @@ def publish_one(%{inbox: inbox, json: json, actor: actor, id: id}) do
     Logger.info("Federating #{id} to #{inbox}")
     host = URI.parse(inbox).host
     signature = Pleroma.Web.HTTPSignatures.sign(actor, %{host: host, "content-length": byte_size(json)})
-    @httpoison.post(inbox, json, [{"Content-Type", "application/activity+json"}, {"signature", signature}])
+    @httpoison.post(inbox, json, [{"Content-Type", "application/activity+json"}, {"signature", signature}], hackney: [pool: :default])
   end
 
   # TODO:

lib/pleroma/web/federator/federator.ex

@@ -96,7 +96,7 @@ def handle(:publish_single_websub, %{xml: xml, topic: topic, callback: callback,
     with {:ok, %{status_code: code}} <- @httpoison.post(callback, xml, [
                   {"Content-Type", "application/atom+xml"},
                   {"X-Hub-Signature", "sha1=#{signature}"}
-                ], timeout: 10000, recv_timeout: 20000) do
+                ], timeout: 10000, recv_timeout: 20000, hackney: [pool: :default]) do
       Logger.debug(fn -> "Pushed to #{callback}, code #{code}" end)
     else e ->
         Logger.debug(fn -> "Couldn't push to #{callback}, #{inspect(e)}" end)

lib/pleroma/web/media_proxy/controller.ex

@@ -3,7 +3,7 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
   require Logger
 
   @httpoison Application.get_env(:pleroma, :httpoison)
-  
+
   @max_body_length 25 * 1048576
 
   @cache_control %{
@@ -31,7 +31,7 @@ def remote(conn, %{"sig" => sig, "url" => url}) do
 
   defp proxy_request(link) do
     headers = [{"user-agent", "Pleroma/MediaProxy; #{Pleroma.Web.base_url()} <#{Application.get_env(:pleroma, :instance)[:email]}>"}]
-    options = @httpoison.process_request_options([:insecure, {:follow_redirect, true}])
+    options = @httpoison.process_request_options([:insecure, {:follow_redirect, true}]) ++ [{:pool, :default}]
     with \
       {:ok, 200, headers, client} <- :hackney.request(:get, link, headers, "", options),
       headers = Enum.into(headers, Map.new),

lib/pleroma/web/salmon/salmon.ex

@@ -147,7 +147,7 @@ def remote_users(%{data: %{"to" => to} = data}) do
   end
 
   defp send_to_user(%{info: %{"salmon" => salmon}}, feed, poster) do
-    with {:ok, %{status_code: code}} <- poster.(salmon, feed, [{"Content-Type", "application/magic-envelope+xml"}], timeout: 10000, recv_timeout: 20000) do
+    with {:ok, %{status_code: code}} <- poster.(salmon, feed, [{"Content-Type", "application/magic-envelope+xml"}], timeout: 10000, recv_timeout: 20000, hackney: [pool: :default]) do
       Logger.debug(fn -> "Pushed to #{salmon}, code #{code}" end)
     else
       e -> Logger.debug(fn -> "Pushing salmon to #{salmon} failed, #{inspect(e)}" end)

test/support/httpoison_mock.ex

@@ -450,4 +450,8 @@ def get(url, body, headers) do
   def post(url, body, headers) do
     {:error, "Not implemented the mock response for post #{inspect(url)}"}
   end
+
+  def post(url, body, headers, options) do
+    {:error, "Not implemented the mock response for post #{inspect(url)}"}
+  end
 end