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Add adapted version of maglev for multi-dc

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This commit is contained in:
Alex Auvolat 2021-02-21 19:14:28 +01:00
parent 24f924afdb
commit 1abbca37c4
1 changed files with 76 additions and 2 deletions
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78
script/simulate_ring.py
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@ -60,7 +60,7 @@ def method1(nodes):
def method2(nodes):
partition_bits = 10
partition_bits = 8
partitions = list(range(2**partition_bits))
def partition_node(i):
h, hn, hndc = None, None, None
@ -92,7 +92,7 @@ def method2(nodes):
def method3(nodes):
partition_bits = 10
partition_bits = 8
queues = []
for (node_id, node_dc, n_tokens) in nodes:
@ -130,6 +130,62 @@ def method3(nodes):
return walk_ring
def method4(nodes):
partition_bits = 8
max_replicas = 3
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):
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)]
que.sort(key=lambda x: x[1])
que = [x[0] for x in que]
queues.append((node_id, node_dc, n_tokens, que))
queues.sort(key=lambda x: hash_str("{} {}".format(ri, x[0])))
remaining = 2**partition_bits
while remaining > 0:
for toktok in range(100):
for iq in range(len(queues)):
node_id, node_dc, n_tokens, node_queue = queues[iq]
if toktok >= n_tokens:
continue
for qi, qv in enumerate(node_queue):
if len(partitions[qv]) != ri:
continue
p_dcs = set([x[0] for x in partitions[qv]])
p_nodes = [x[1] for x in partitions[qv]]
if node_dc not in p_dcs or (len(p_dcs) == len(dcs) and node_id not in p_nodes):
partitions[qv].append((node_dc, node_id))
remaining -= 1
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):
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))
return [node_id for _, node_id in partitions[i]]
return walk_ring
def evaluate_method(walk_ring):
node_data_counts = {}
for i in range(100000):
@ -175,3 +231,21 @@ if __name__ == "__main__":
]
method3_walk_ring = method3(nodes)
evaluate_method(method3_walk_ring)
print("------")
print("method 4 (maglev, multi-dc twist)")
nodes = [('digitale', 'atuin', 8),
('drosera', 'atuin', 8),
('datura', 'atuin', 8),
('io', 'jupiter', 16),
('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)