Merge #154106

154106: asim: isolate RandSource between modes r=tbg a=wenyihu6

Epic: CRDB-49117 
Release note: none

---
**asim: isolate RandSource between modes**

Previously, the same RandSource was shared across configurations, making
comparisons between modes less reliable. This commit updates the logic
so that each configuration initializes its own RandSource, ensuring consistent
and isolated behavior.



Co-authored-by: wenyihu6 <[email protected]>

Author: craig[bot]

pkg/kv/kvserver/asim/tests/datadriven_simulation_test.go

@@ -494,7 +494,6 @@ func TestDataDriven(t *testing.T) {
 					metricsMap[s] = struct{}{}
 				}
 
-				seedGen := rand.New(rand.NewSource(seed))
 				require.NotZero(t, rangeGen)
 
 				knownConfigurations := map[string]func(eg *gen.StaticEvents){
@@ -555,6 +554,7 @@ func TestDataDriven(t *testing.T) {
 						// parameter to the `eval` command.
 						testName := name + "_" + mv
 
+						seedGen := rand.New(rand.NewSource(seed))
 						for sample := 0; sample < samples; sample++ {
 							recIdx := map[int64]int{}
 							settingsGen.Settings.OnRecording = func(storeID int64, rec tracingpb.Recording) {

pkg/kv/kvserver/asim/tests/testdata/generated/example_rebalancing/example_rebalancing_mma-only_1.json

@@ -30,5 +30,5 @@ eval duration=20m cfgs=(sma-count,mma-only)
 ----
 artifacts[sma-count]: 8e9d6ada04cb9561
 ==========================
-artifacts[mma-only]: 239144d63ffded95
+artifacts[mma-only]: 8d6fbe46b5c14575
 ==========================

pkg/kv/kvserver/asim/tests/testdata/generated/example_rebalancing/example_rebalancing_mma-only_2.json

@@ -30,5 +30,5 @@ eval duration=10m cfgs=(sma-count,mma-only)
 ----
 artifacts[sma-count]: 79c6ee6ca7f1ab55
 ==========================
-artifacts[mma-only]: d508ef8005542825
+artifacts[mma-only]: 79c6ee6ca7f1ab55
 ==========================

pkg/kv/kvserver/asim/tests/testdata/non_rand/decommission_conformance.txt

@@ -32,17 +32,17 @@ artifacts[sma-count]: f36a73f72b67ff15
 ==========================
 disk_fraction_used#1: first: [s1=0.20, s2=0.20, s3=0.20, s4=0.20, s5=1.05] (stddev=0.34, mean=0.37, sum=2)
 disk_fraction_used#1: last:  [s1=0.31, s2=0.31, s3=0.31, s4=0.29, s5=0.92] (stddev=0.25, mean=0.43, sum=2)
-disk_fraction_used#1: thrash_pct: [s1=2%, s2=1%, s3=1%, s4=0%, s5=65%]  (sum=69%)
+disk_fraction_used#1: thrash_pct: [s1=2%, s2=2%, s3=1%, s4=0%, s5=65%]  (sum=69%)
 replicas#1: first: [s1=300, s2=300, s3=300, s4=300, s5=300] (stddev=0.00, mean=300.00, sum=1500)
-replicas#1: last:  [s1=331, s2=329, s3=329, s4=316, s5=195] (stddev=52.77, mean=300.00, sum=1500)
-replicas#1: thrash_pct: [s1=16%, s2=7%, s3=6%, s4=0%, s5=0%]  (sum=29%)
-artifacts[mma-only]: 4bbec1a9787ddb71
+replicas#1: last:  [s1=330, s2=330, s3=331, s4=315, s5=194] (stddev=53.33, mean=300.00, sum=1500)
+replicas#1: thrash_pct: [s1=11%, s2=11%, s3=6%, s4=0%, s5=0%]  (sum=27%)
+artifacts[mma-only]: e2b0680f69bcdea0
 ==========================
 disk_fraction_used#1: first: [s1=0.20, s2=0.20, s3=0.20, s4=0.20, s5=1.05] (stddev=0.34, mean=0.37, sum=2)
-disk_fraction_used#1: last:  [s1=0.30, s2=0.30, s3=0.30, s4=0.30, s5=0.93] (stddev=0.25, mean=0.43, sum=2)
-disk_fraction_used#1: thrash_pct: [s1=37%, s2=35%, s3=37%, s4=33%, s5=174%]  (sum=316%)
+disk_fraction_used#1: last:  [s1=0.30, s2=0.31, s3=0.30, s4=0.30, s5=0.92] (stddev=0.25, mean=0.43, sum=2)
+disk_fraction_used#1: thrash_pct: [s1=40%, s2=36%, s3=37%, s4=37%, s5=149%]  (sum=298%)
 replicas#1: first: [s1=300, s2=300, s3=300, s4=300, s5=300] (stddev=0.00, mean=300.00, sum=1500)
-replicas#1: last:  [s1=327, s2=326, s3=328, s4=323, s5=196] (stddev=52.03, mean=300.00, sum=1500)
-replicas#1: thrash_pct: [s1=280%, s2=266%, s3=277%, s4=248%, s5=181%]  (sum=1252%)
-artifacts[mma-count]: 2a17b81d800bb09
+replicas#1: last:  [s1=326, s2=329, s3=323, s4=328, s5=194] (stddev=53.04, mean=300.00, sum=1500)
+replicas#1: thrash_pct: [s1=303%, s2=271%, s3=282%, s4=274%, s5=141%]  (sum=1271%)
+artifacts[mma-count]: 94eb963d0fe016b1
 ==========================

pkg/kv/kvserver/asim/tests/testdata/non_rand/example_conformance.txt

@@ -38,7 +38,7 @@ leases#1: thrash_pct: [s1=0%, s2=0%, s3=0%, s4=0%, s5=0%]  (sum=0%)
 replicas#1: first: [s1=500, s2=456, s3=262, s4=165, s5=117] (stddev=153.29, mean=300.00, sum=1500)
 replicas#1: last:  [s1=500, s2=456, s3=262, s4=165, s5=117] (stddev=153.29, mean=300.00, sum=1500)
 replicas#1: thrash_pct: [s1=0%, s2=0%, s3=0%, s4=0%, s5=0%]  (sum=0%)
-artifacts[mma-only]: 752089ccd9817df9
+artifacts[mma-only]: 88981cebae8fb4b9
 failed assertion sample 1
   stat=replicas value=(=0.00) ticks=5
 	store=5 stat=117.00

pkg/kv/kvserver/asim/tests/testdata/non_rand/example_fulldisk.txt

@@ -32,5 +32,5 @@ eval duration=10m cfgs=(sma-count,mma-only)
 ----
 artifacts[sma-count]: 35051da9f3ec651d
 ==========================
-artifacts[mma-only]: 5c6a18fd5194eefd
+artifacts[mma-only]: 339579f79e6b26fd
 ==========================

pkg/kv/kvserver/asim/tests/testdata/non_rand/example_io_overload.txt

@@ -43,10 +43,10 @@ replicas#1: thrash_pct: [s1=0%, s2=0%, s3=0%, s4=0%, s5=0%, s6=16%, s7=0%]  (sum
 artifacts[sma-count]: 6ea963e52d5dbdcd
 ==========================
 leases#1: first: [s1=100, s2=100, s3=100, s4=100, s5=100, s6=100, s7=100] (stddev=0.00, mean=100.00, sum=700)
-leases#1: last:  [s1=134, s2=139, s3=140, s4=151, s5=136, s6=0, s7=0] (stddev=63.44, mean=100.00, sum=700)
-leases#1: thrash_pct: [s1=0%, s2=0%, s3=0%, s4=0%, s5=0%, s6=22%, s7=0%]  (sum=22%)
+leases#1: last:  [s1=133, s2=138, s3=146, s4=139, s5=144, s6=0, s7=0] (stddev=63.37, mean=100.00, sum=700)
+leases#1: thrash_pct: [s1=0%, s2=0%, s3=0%, s4=0%, s5=0%, s6=23%, s7=0%]  (sum=23%)
 replicas#1: first: [s1=300, s2=300, s3=300, s4=300, s5=300, s6=300, s7=300] (stddev=0.00, mean=300.00, sum=2100)
-replicas#1: last:  [s1=431, s2=415, s3=418, s4=419, s5=417, s6=0, s7=0] (stddev=189.80, mean=300.00, sum=2100)
-replicas#1: thrash_pct: [s1=0%, s2=0%, s3=0%, s4=0%, s5=0%, s6=14%, s7=0%]  (sum=14%)
-artifacts[mma-only]: e00a4da1eb04fbff
+replicas#1: last:  [s1=434, s2=414, s3=419, s4=415, s5=418, s6=0, s7=0] (stddev=189.84, mean=300.00, sum=2100)
+replicas#1: thrash_pct: [s1=0%, s2=0%, s3=0%, s4=0%, s5=0%, s6=16%, s7=0%]  (sum=16%)
+artifacts[mma-only]: aff8bd0fa94243e1
 ==========================

pkg/kv/kvserver/asim/tests/testdata/non_rand/example_lease_preferences.txt

@@ -27,15 +27,15 @@ leases#1: thrash_pct: [s1=0%, s2=0%, s3=0%, s4=0%, s5=0%, s6=0%, s7=0%, s8=25%,
 artifacts[sma-count]: 6322c40ff6c7b47c
 ==========================
 leases#1: first: [s1=8, s2=3, s3=0, s4=0, s5=0, s6=0, s7=0, s8=0, s9=1, s10=0, s11=1, s12=0, s13=1, s14=0] (stddev=2.10, mean=1.00, sum=14)
-leases#1: last:  [s1=4, s2=1, s3=0, s4=0, s5=0, s6=1, s7=0, s8=0, s9=1, s10=1, s11=1, s12=1, s13=2, s14=2] (stddev=1.07, mean=1.00, sum=14)
-leases#1: thrash_pct: [s1=0%, s2=0%, s3=0%, s4=0%, s5=0%, s6=0%, s7=0%, s8=0%, s9=0%, s10=0%, s11=25%, s12=0%, s13=0%, s14=0%]  (sum=25%)
-artifacts[mma-only]: ed1b3ca87bbb8148
+leases#1: last:  [s1=2, s2=1, s3=1, s4=0, s5=0, s6=1, s7=1, s8=1, s9=1, s10=1, s11=2, s12=1, s13=1, s14=1] (stddev=0.53, mean=1.00, sum=14)
+leases#1: thrash_pct: [s1=0%, s2=0%, s3=25%, s4=0%, s5=0%, s6=0%, s7=0%, s8=0%, s9=0%, s10=0%, s11=52%, s12=0%, s13=0%, s14=0%]  (sum=77%)
+artifacts[mma-only]: 1aecc80254de0a63
 failed assertion sample 1
   balance stat=leases threshold=(≤1.00) ticks=6
-	max/mean=4.00 tick=0
-	max/mean=4.00 tick=1
-	max/mean=4.00 tick=2
-	max/mean=4.00 tick=3
-	max/mean=4.00 tick=4
-	max/mean=4.00 tick=5
+	max/mean=2.00 tick=0
+	max/mean=2.00 tick=1
+	max/mean=2.00 tick=2
+	max/mean=2.00 tick=3
+	max/mean=2.00 tick=4
+	max/mean=2.00 tick=5
 ==========================