fix github actions failing latency test for active defrag - part 2

it seems that running two clients at a time is ok too, resuces action
time from 20 minutes to 10. we'll use this for now, and if one day it
won't be enough we'll have to run just the sensitive tests one by one
separately from the others.

this commit also fixes an issue with the defrag test that appears to be
very rare.

.github/workflows/ci.yml

@@ -12,9 +12,9 @@ jobs:
     - name: test
       run: |
         sudo apt-get install tcl8.5
-        ./runtest --clients 1 --verbose
+        ./runtest --clients 2 --verbose
 
-  test-ubuntu-old:
+  build-ubuntu-old:
     runs-on: ubuntu-16.04
     steps:
     - uses: actions/checkout@v1

tests/unit/memefficiency.tcl

@@ -60,6 +60,7 @@ start_server {tags {"defrag"}} {
 
             r config set latency-monitor-threshold 5
             r latency reset
+            r config set maxmemory 110mb ;# prevent further eviction (not to fail the digest test)
             set digest [r debug digest]
             catch {r config set activedefrag yes} e
             if {![string match {DISABLED*} $e]} {
@@ -166,7 +167,7 @@ start_server {tags {"defrag"}} {
             for {set j 0} {$j < 500000} {incr j} {
                 $rd read ; # Discard replies
             }
-            assert {[r dbsize] == 500010}
+            assert_equal [r dbsize] 500010
 
             # create some fragmentation
             for {set j 0} {$j < 500000} {incr j 2} {
@@ -175,7 +176,7 @@ start_server {tags {"defrag"}} {
             for {set j 0} {$j < 500000} {incr j 2} {
                 $rd read ; # Discard replies
             }
-            assert {[r dbsize] == 250010}
+            assert_equal [r dbsize] 250010
 
             # start defrag
             after 120 ;# serverCron only updates the info once in 100ms