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Simulate stuff moving around

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This commit is contained in:
Alex Auvolat 2021-02-25 10:53:33 +01:00
parent 5fe95ebae7
commit 49c25a1509
2 changed files with 110 additions and 68 deletions
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175
script/simulate_ring.py Normal file → Executable file
View file

@ -1,6 +1,11 @@
#!/usr/bin/env python3
import hashlib
import bisect
import xxhash
import numpy as np
REPLICATION_FACTOR = 3
def hash_str(s):
xxh = xxhash.xxh64()
@ -10,11 +15,11 @@ def hash_str(s):
def sha256_str(s):
return hashlib.sha256(s.encode('ascii')).hexdigest()
def walk_ring_from_pos(tokens, dcs, start, rep):
def walk_ring_from_pos(tokens, dcs, start):
ret = []
ret_dcs = set()
delta = 0
while len(ret) < rep:
while len(ret) < REPLICATION_FACTOR:
i = (start + delta) % len(tokens)
delta = delta + 1
@ -26,6 +31,7 @@ def walk_ring_from_pos(tokens, dcs, start, rep):
ret.append(token_node)
return ret
"""
def count_tokens_per_node(tokens):
tokens_of_node = {}
for _, _, token_node in tokens:
@ -34,7 +40,19 @@ def count_tokens_per_node(tokens):
tokens_of_node[token_node] += 1
print("#tokens per node:")
for node, ntok in sorted(list(tokens_of_node.items())):
print(node, ": ", ntok)
print("-", node, ": ", ntok)
"""
def count_partitions_per_node(ring_node_list):
tokens_of_node = {}
for nodelist in ring_node_list:
for node_id in nodelist:
if node_id not in tokens_of_node:
tokens_of_node[node_id] = 0
tokens_of_node[node_id] += 1
print("#partitions per node:")
for node, ntok in sorted(list(tokens_of_node.items())):
print("-", node, ": ", ntok)
def method1(nodes):
@ -47,20 +65,19 @@ def method1(nodes):
tokens.append((token, dc, node_id))
tokens.sort(key=lambda tok: tok[0])
#print(tokens)
count_tokens_per_node(tokens)
space_of_node = {}
def walk_ring(v, rep):
def walk_ring(v):
i = bisect.bisect_left([tok for tok, _, _ in tokens], hash_str(v))
return walk_ring_from_pos(tokens, dcs, i, rep)
return walk_ring_from_pos(tokens, dcs, i)
return walk_ring
ring_node_list = [walk_ring_from_pos(tokens, dcs, i) for i in range(len(tokens))]
return walk_ring, ring_node_list
def method2(nodes):
partition_bits = 8
partition_bits = 10
partitions = list(range(2**partition_bits))
def partition_node(i):
h, hn, hndc = None, None, None
@ -74,25 +91,26 @@ def method2(nodes):
return (i, hndc, hn)
partition_nodes = [partition_node(i) for i in partitions]
count_tokens_per_node(partition_nodes)
dcs = list(set(node_dc for _, node_dc, _ in nodes))
def walk_ring(v, rep):
def walk_ring(v):
# xxh = xxhash.xxh32()
# xxh.update(v.encode('ascii'))
# vh = xxh.intdigest()
# i = vh % (2**partition_bits)
vh = hashlib.sha256(v.encode('ascii')).digest()
i = (vh[0]<<8 | vh[1]) % (2**partition_bits)
return walk_ring_from_pos(partition_nodes, dcs, i, rep)
return walk_ring_from_pos(partition_nodes, dcs, i)
return walk_ring
ring_node_list = [walk_ring_from_pos(partition_nodes, dcs, i) for i in range(len(partition_nodes))]
return walk_ring, ring_node_list
def method3(nodes):
partition_bits = 8
partition_bits = 10
queues = []
for (node_id, node_dc, n_tokens) in nodes:
@ -119,27 +137,27 @@ def method3(nodes):
queues[iq] = (node_id, node_dc, n_tokens, node_queue[qi+1:])
break
count_tokens_per_node(partitions)
dcs = list(set(node_dc for _, node_dc, _ in nodes))
def walk_ring(v, rep):
def walk_ring(v):
vh = hashlib.sha256(v.encode('ascii')).digest()
i = (vh[0]<<8 | vh[1]) % (2**partition_bits)
return walk_ring_from_pos(partitions, dcs, i, rep)
return walk_ring_from_pos(partitions, dcs, i)
return walk_ring
ring_node_list = [walk_ring_from_pos(partitions, dcs, i) for i in range(len(partitions))]
return walk_ring, ring_node_list
def method4(nodes):
partition_bits = 8
max_replicas = 3
partition_bits = 10
partitions = [[] for _ in range(2**partition_bits)]
dcs = list(set(node_dc for _, node_dc, _ in nodes))
# Maglev, improved for several replicas on several DCs
for ri in range(max_replicas):
for ri in range(REPLICATION_FACTOR):
queues = []
for (node_id, node_dc, n_tokens) in nodes:
que = [(i, hash_str(f"{node_id} {i}")) for i in range(2**partition_bits)]
@ -167,36 +185,58 @@ def method4(nodes):
queues[iq] = (node_id, node_dc, n_tokens, node_queue[qi+1:])
break
# count
tokens_of_node = {}
for nodelist in partitions:
for node_dc, node_id in nodelist:
if node_id not in tokens_of_node:
tokens_of_node[node_id] = 0
tokens_of_node[node_id] += 1
print("#tokens per node:")
for node, ntok in sorted(list(tokens_of_node.items())):
print(node, ": ", ntok)
def walk_ring(v, rep):
def walk_ring(v):
vh = hashlib.sha256(v.encode('ascii')).digest()
i = (vh[0]<<8 | vh[1]) % (2**partition_bits)
assert len(set([node_dc for node_dc, _ in partitions[i]])) == min(max_replicas, len(dcs))
assert len(set([node_dc for node_dc, _ in partitions[i]])) == min(REPLICATION_FACTOR, len(dcs))
return [node_id for _, node_id in partitions[i]]
return walk_ring
ring_node_list = [[node_id for _, node_id in p] for p in partitions]
def evaluate_method(walk_ring):
return walk_ring, ring_node_list
def evaluate_method(method, nodes):
walk_ring, ring_node_list = method(nodes)
print("Ring length:", len(ring_node_list))
count_partitions_per_node(ring_node_list)
print("Number of data items per node (100000 simulation):")
node_data_counts = {}
for i in range(100000):
nodes = walk_ring(f"{i}", 3)
for n in nodes:
inodes = walk_ring(f"{i}")
for n in inodes:
if n not in node_data_counts:
node_data_counts[n] = 0
node_data_counts[n] += 1
print("Number of data items per node:")
for n, v in sorted(list(node_data_counts.items())):
print(n, ": ", v)
print("-", n, ": ", v)
dclist_per_ntok = {}
for node_id, _, ntok in nodes:
if ntok not in dclist_per_ntok:
dclist_per_ntok[ntok] = []
dclist_per_ntok[ntok].append(node_data_counts[node_id])
list_normalized = []
for ntok, dclist in dclist_per_ntok.items():
avg = sum(dclist)/len(dclist)
for v in dclist:
list_normalized.append(v / avg)
print("variance wrt. same-ntok mean:", "%.2f%%"%(np.var(list_normalized)*100))
num_changes_sum = [0, 0, 0, 0]
for n in nodes:
nodes2 = [nn for nn in nodes if nn != n]
_, ring_node_list_2 = method(nodes2)
if len(ring_node_list_2) != len(ring_node_list):
continue
num_changes = [0, 0, 0, 0]
for (ns1, ns2) in zip(ring_node_list, ring_node_list_2):
changes = sum(1 for x in ns1 if x not in ns2)
num_changes[changes] += 1
for i, v in enumerate(num_changes):
num_changes_sum[i] += v / len(ring_node_list)
print("removing", n[1], n[0], ":", " ".join(["%.2f%%"%(x*100/len(ring_node_list)) for x in num_changes]))
print("1-node removal: partitions moved on 0/1/2/3 nodes: ", " ".join(["%.2f%%"%(x*100/len(nodes)) for x in num_changes_sum]))
if __name__ == "__main__":
@ -206,46 +246,45 @@ if __name__ == "__main__":
('drosera', 'atuin', 64),
('datura', 'atuin', 64),
('io', 'jupiter', 128)]
method1_walk_ring = method1(nodes)
evaluate_method(method1_walk_ring)
nodes2 = [('digitale', 'atuin', 64),
('drosera', 'atuin', 64),
('datura', 'atuin', 64),
('io', 'jupiter', 128),
('isou', 'jupiter', 64),
('mini', 'grog', 32),
('mixi', 'grog', 32),
('moxi', 'grog', 32),
('modi', 'grog', 32),
('geant', 'grisou', 128),
('gipsie', 'grisou', 128),
]
evaluate_method(method1, nodes2)
print("------")
print("method 2 (custom ring)")
nodes = [('digitale', 'atuin', 10),
('drosera', 'atuin', 10),
('datura', 'atuin', 10),
('io', 'jupiter', 20)]
method2_walk_ring = method2(nodes)
evaluate_method(method2_walk_ring)
print("------")
print("method 3 (maglev)")
nodes = [('digitale', 'atuin', 4),
('drosera', 'atuin', 4),
('datura', 'atuin', 4),
('io', 'jupiter', 8),
#('mini', 'grog', 2),
#('mixi', 'grog', 2),
#('moxi', 'grog', 2),
#('modi', 'grog', 2),
]
method3_walk_ring = method3(nodes)
evaluate_method(method3_walk_ring)
print("------")
print("method 4 (maglev, multi-dc twist)")
nodes = [('digitale', 'atuin', 8),
('io', 'jupiter', 8)]
nodes2 = [('digitale', 'atuin', 8),
('drosera', 'atuin', 8),
('datura', 'atuin', 8),
('io', 'jupiter', 16),
('isou', 'jupiter', 8),
('mini', 'grog', 4),
('mixi', 'grog', 4),
('moxi', 'grog', 4),
('modi', 'grog', 4),
('geant', 'grisou', 16),
('gipsie', 'grisou', 16),
#('isou', 'jupiter', 8),
]
method4_walk_ring = method4(nodes)
evaluate_method(method4_walk_ring)
evaluate_method(method2, nodes2)
print("------")
print("method 3 (maglev)")
evaluate_method(method3, nodes2)
print("------")
print("method 4 (maglev, multi-dc twist)")
evaluate_method(method4, nodes2)

3
src/model/block.rs
View file

@ -426,6 +426,9 @@ impl BlockManager {
}
fn repair_aux_read_dir_rec<'a>(&'a self, path: &'a PathBuf, must_exit: &'a watch::Receiver<bool>) -> BoxFuture<'a, Result<(), Error>> {
// Lists all blocks on disk and adds them to the resync queue.
// This allows us to find blocks we are storing but don't actually need,
// so that we can offload them if necessary and then delete them locally.
async move {
let mut ls_data_dir = fs::read_dir(path).await?;
while let Some(data_dir_ent) = ls_data_dir.next().await {