Fix unstable tests on slow machines.

Few tests had borderline thresholds that were adjusted.

The slave buffers test had two issues, preventing the slave buffer from growing:
1) the slave didn't necessarily go to sleep on time, or woke up too early,
   now using SIGSTOP to make sure it goes to sleep exactly when we want.
2) the master disconnected the slave on timeout

tests/unit/dump.tcl

@@ -33,7 +33,7 @@ start_server {tags {"dump"}} {
         set now [clock milliseconds]
         r restore foo [expr $now+3000] $encoded absttl
         set ttl [r pttl foo]
-        assert {$ttl >= 2998 && $ttl <= 3000}
+        assert {$ttl >= 2990 && $ttl <= 3000}
         r get foo
     } {bar}
     
@@ -44,7 +44,7 @@ start_server {tags {"dump"}} {
         r config set maxmemory-policy allkeys-lru
         r restore foo 0 $encoded idletime 1000
         set idle [r object idletime foo]
-        assert {$idle >= 1000 && $idle <= 1002}
+        assert {$idle >= 1000 && $idle <= 1010}
         r get foo
     } {bar}
     

tests/unit/maxmemory.tcl

@@ -143,9 +143,11 @@ start_server {tags {"maxmemory"}} {
     }
 }
 
-proc test_slave_buffers {cmd_count payload_len limit_memory pipeline} {
+proc test_slave_buffers {test_name cmd_count payload_len limit_memory pipeline} {
     start_server {tags {"maxmemory"}} {
         start_server {} {
+        set slave_pid [s process_id]
+        test "$test_name" {
             set slave [srv 0 client]
             set slave_host [srv 0 host]
             set slave_port [srv 0 port]
@@ -158,8 +160,10 @@ proc test_slave_buffers {cmd_count payload_len limit_memory pipeline} {
                 $master setrange "key:$j" 100000 asdf
             }
 
+            # make sure master doesn't disconnect slave because of timeout
+            $master config set repl-timeout 300 ;# 5 minutes
             $master config set maxmemory-policy allkeys-random
-            $master config set client-output-buffer-limit "slave 100000000 100000000 60"
+            $master config set client-output-buffer-limit "slave 100000000 100000000 300"
             $master config set repl-backlog-size [expr {10*1024}]
 
             $slave slaveof $master_host $master_port
@@ -182,9 +186,9 @@ proc test_slave_buffers {cmd_count payload_len limit_memory pipeline} {
 
             # put the slave to sleep
             set rd_slave [redis_deferring_client]
-            $rd_slave debug sleep 300
+            exec kill -SIGSTOP $slave_pid
 
-            # send some 10mb woth of commands that don't increase the memory usage
+            # send some 10mb worth of commands that don't increase the memory usage
             if {$pipeline == 1} {
                 set rd_master [redis_deferring_client -1]
                 for {set k 0} {$k < $cmd_count} {incr k} {
@@ -218,19 +222,21 @@ proc test_slave_buffers {cmd_count payload_len limit_memory pipeline} {
             set delta_no_repl [expr {$killed_used_no_repl - $used_no_repl}]
             assert {$killed_slave_buf == 0}
             assert {$delta_no_repl > -50*1024 && $delta_no_repl < 50*1024} ;# 1 byte unaccounted for, with 1M commands will consume some 1MB
+
+        }
+        # unfreeze slave process (after the 'test' succeeded or failed, but before we attempt to terminate the server
+        exec kill -SIGCONT $slave_pid
         }
     }
 }
 
-test {slave buffer are counted correctly} {
-    # we wanna use many small commands, and we don't wanna wait long
-    # so we need to use a pipeline (redis_deferring_client)
-    # that may cause query buffer to fill and induce eviction, so we disable it
-    test_slave_buffers 1000000 10 0 1
-}
+# test that slave buffer are counted correctly
+# we wanna use many small commands, and we don't wanna wait long
+# so we need to use a pipeline (redis_deferring_client)
+# that may cause query buffer to fill and induce eviction, so we disable it
+test_slave_buffers {slave buffer are counted correctly} 1000000 10 0 1
 
-test {slave buffer don't induce eviction} {
-    # test again with fewer (and bigger) commands without pipeline, but with eviction
-    test_slave_buffers 100000 100 1 0
-}
+# test that slave buffer don't induce eviction
+# test again with fewer (and bigger) commands without pipeline, but with eviction
+test_slave_buffers "slave buffer don't induce eviction" 100000 100 1 0
 

tests/unit/memefficiency.tcl

@@ -201,7 +201,7 @@ start_server {tags {"defrag"}} {
                 assert {$frag < 1.1}
                 # due to high fragmentation, 10hz, and active-defrag-cycle-max set to 75,
                 # we expect max latency to be not much higher than 75ms
-                assert {$max_latency <= 80}
+                assert {$max_latency <= 120}
             }
             # verify the data isn't corrupted or changed
             set newdigest [r debug digest]