test_tablets / test_tablets_migration take 20 minutes in debug mode

[avikivity]

1210.32444691658|debug|test_tablets
1199.00373029709|debug|test_tablets_migration

[raphaelsc]

test_tablets_migration is essentially about bringing nodes down during different stages of migration, to simulate failure and possibly revert migrations depending on the stage. I wonder if we can reduce the test time by tweaking the failure detector settings

[raphaelsc]

turns out test_tablets_migration tried to adjust failure detector already, but it was limited by the echo interval. the test runtime can be reduced by 10% with the following changes:

diff --git a/test/topology_custom/test_tablets_migration.py b/test/topology_custom/test_tablets_migration.py
index 678668f59f..2e1e3e3a91 100644
--- a/test/topology_custom/test_tablets_migration.py
+++ b/test/topology_custom/test_tablets_migration.py
@@ -103,7 +103,8 @@ async def test_node_failure_during_tablet_migration(manager: ManagerClient, fail
         pytest.skip('Failing source during target cleanup is pointless')
 
     logger.info("Bootstrapping cluster")
-    cfg = {'enable_user_defined_functions': False, 'enable_tablets': True, 'failure_detector_timeout_in_ms': 2000}
+    cfg = {'enable_user_defined_functions': False, 'enable_tablets': True, 'failure_detector_timeout_in_ms': 200,
+           'error_injections_at_startup': ['gossiper_reduced_echo_interval']}
     host_ids = []
     servers = []
 
diff --git a/gms/gossiper.cc b/gms/gossiper.cc
index 68dc609c69..bac0a0ec4d 100644
--- a/gms/gossiper.cc
+++ b/gms/gossiper.cc
@@ -979,7 +979,7 @@ future<std::set<inet_address>> gossiper::get_unreachable_members_synchronized()
 future<> gossiper::failure_detector_loop_for_node(gms::inet_address node, generation_type gossip_generation, uint64_t live_endpoints_version) {
     auto last = gossiper::clk::now();
     auto diff = gossiper::clk::duration(0);
-    auto echo_interval = std::chrono::milliseconds(2000);
+    auto echo_interval = utils::get_local_injector().enter("gossiper_reduced_echo_interval") ? std::chrono::milliseconds(200) : std::chrono::milliseconds(2000);
     auto max_duration = echo_interval + std::chrono::milliseconds(_gcfg.failure_detector_timeout_ms());
     while (is_enabled()) {
         bool failed = false;