non recursive version of method gomory_hu_tree for graphs
#38791
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Documentation preview for this PR (built with commit b844daa; changes) is ready! 🎉 |
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@maxale, this is ready to be reviewed. |
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I'm slow to respond in the coming few days. We've just moved Oxford U. -> Northwestern U. |
vbraun
pushed a commit
to vbraun/sage
that referenced
this pull request
Nov 8, 2024
…r graphs
This PR implements a non recursive version of method `gomory_hu_tree`
for graphs. This fixes the max recursion depth error reported in
https://ask.sagemath.org/question/79577/graphs-gomory-hu-tree-memory-
blow-up-and-max-recursion-depth/. The memory consumption is seriously
reduced.
Without this PR:
```py
sage: def test(g):
....: from datetime import datetime
....: import psutil
....: start_time = datetime.now()
....: process = psutil.Process(os.getpid())
....: mem = process.memory_info()[0] / float(2 ** 20)
....: print("Mem usage at start:", mem, "MiB")
....: try:
....: print("Vertices found:", g.order(), "and edges:",
g.size())
....: T = g.gomory_hu_tree(algorithm="FF")
....: except Exception as error:
....: print("Error detected:", error)
....: finally:
....: end_time = datetime.now()
....: print("Runtime =", end_time - start_time)
....: mem = process.memory_info()[0] / float(2 ** 20)
....: print("Mem usage at end:", mem, "MiB")
....:
sage: test(graphs.SierpinskiGasketGraph(5))
Mem usage at start: 241.0234375 MiB
Vertices found: 123 and edges: 243
Runtime = 0:00:00.243477
Mem usage at end: 252.1171875 MiB
sage: test(graphs.SierpinskiGasketGraph(6))
Mem usage at start: 252.1171875 MiB
Vertices found: 366 and edges: 729
Runtime = 0:00:02.050924
Mem usage at end: 324.30078125 MiB
sage: test(graphs.SierpinskiGasketGraph(7))
Mem usage at start: 324.30078125 MiB
Vertices found: 1095 and edges: 2187
Runtime = 0:00:21.207451
Mem usage at end: 968.97265625 MiB
sage: test(graphs.SierpinskiGasketGraph(8))
Mem usage at start: 950.25390625 MiB
Vertices found: 3282 and edges: 6561
Error detected: maximum recursion depth exceeded
Runtime = 0:04:36.154550
Mem usage at end: 6767.39453125 MiB
```
With this PR
```py
sage: test(graphs.SierpinskiGasketGraph(5))
Mem usage at start: 246.0859375 MiB
Vertices found: 123 and edges: 243
Runtime = 0:00:00.219925
Mem usage at end: 246.7109375 MiB
sage: test(graphs.SierpinskiGasketGraph(6))
Mem usage at start: 247.0234375 MiB
Vertices found: 366 and edges: 729
Runtime = 0:00:01.900761
Mem usage at end: 248.2734375 MiB
sage: test(graphs.SierpinskiGasketGraph(7))
Mem usage at start: 248.5859375 MiB
Vertices found: 1095 and edges: 2187
Runtime = 0:00:18.535145
Mem usage at end: 252.4921875 MiB
sage: test(graphs.SierpinskiGasketGraph(8))
Mem usage at start: 253.1171875 MiB
Vertices found: 3282 and edges: 6561
Runtime = 0:02:57.325506
Mem usage at end: 265.15234375 MiB
sage: test(graphs.SierpinskiGasketGraph(9))
Mem usage at start: 263.625 MiB
Vertices found: 9843 and edges: 19683
Runtime = 0:29:03.321870
Mem usage at end: 296.8359375 MiB
sage: test(graphs.SierpinskiGasketGraph(10))
Mem usage at start: 303.11328125 MiB
Vertices found: 29526 and edges: 59049
Runtime = 5:01:45.355463
Mem usage at end: 399.3984375 MiB
```
### :memo: Checklist
<!-- Put an `x` in all the boxes that apply. -->
- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [x] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [x] I have updated the documentation and checked the documentation
preview.
### :hourglass: Dependencies
<!-- List all open PRs that this PR logically depends on. For example,
-->
<!-- - sagemath#12345: short description why this is a dependency -->
<!-- - sagemath#34567: ... -->
URL: sagemath#38791
Reported by: David Coudert
Reviewer(s): Dima Pasechnik
vbraun
pushed a commit
to vbraun/sage
that referenced
this pull request
Nov 9, 2024
…r graphs
This PR implements a non recursive version of method `gomory_hu_tree`
for graphs. This fixes the max recursion depth error reported in
https://ask.sagemath.org/question/79577/graphs-gomory-hu-tree-memory-
blow-up-and-max-recursion-depth/. The memory consumption is seriously
reduced.
Without this PR:
```py
sage: def test(g):
....: from datetime import datetime
....: import psutil
....: start_time = datetime.now()
....: process = psutil.Process(os.getpid())
....: mem = process.memory_info()[0] / float(2 ** 20)
....: print("Mem usage at start:", mem, "MiB")
....: try:
....: print("Vertices found:", g.order(), "and edges:",
g.size())
....: T = g.gomory_hu_tree(algorithm="FF")
....: except Exception as error:
....: print("Error detected:", error)
....: finally:
....: end_time = datetime.now()
....: print("Runtime =", end_time - start_time)
....: mem = process.memory_info()[0] / float(2 ** 20)
....: print("Mem usage at end:", mem, "MiB")
....:
sage: test(graphs.SierpinskiGasketGraph(5))
Mem usage at start: 241.0234375 MiB
Vertices found: 123 and edges: 243
Runtime = 0:00:00.243477
Mem usage at end: 252.1171875 MiB
sage: test(graphs.SierpinskiGasketGraph(6))
Mem usage at start: 252.1171875 MiB
Vertices found: 366 and edges: 729
Runtime = 0:00:02.050924
Mem usage at end: 324.30078125 MiB
sage: test(graphs.SierpinskiGasketGraph(7))
Mem usage at start: 324.30078125 MiB
Vertices found: 1095 and edges: 2187
Runtime = 0:00:21.207451
Mem usage at end: 968.97265625 MiB
sage: test(graphs.SierpinskiGasketGraph(8))
Mem usage at start: 950.25390625 MiB
Vertices found: 3282 and edges: 6561
Error detected: maximum recursion depth exceeded
Runtime = 0:04:36.154550
Mem usage at end: 6767.39453125 MiB
```
With this PR
```py
sage: test(graphs.SierpinskiGasketGraph(5))
Mem usage at start: 246.0859375 MiB
Vertices found: 123 and edges: 243
Runtime = 0:00:00.219925
Mem usage at end: 246.7109375 MiB
sage: test(graphs.SierpinskiGasketGraph(6))
Mem usage at start: 247.0234375 MiB
Vertices found: 366 and edges: 729
Runtime = 0:00:01.900761
Mem usage at end: 248.2734375 MiB
sage: test(graphs.SierpinskiGasketGraph(7))
Mem usage at start: 248.5859375 MiB
Vertices found: 1095 and edges: 2187
Runtime = 0:00:18.535145
Mem usage at end: 252.4921875 MiB
sage: test(graphs.SierpinskiGasketGraph(8))
Mem usage at start: 253.1171875 MiB
Vertices found: 3282 and edges: 6561
Runtime = 0:02:57.325506
Mem usage at end: 265.15234375 MiB
sage: test(graphs.SierpinskiGasketGraph(9))
Mem usage at start: 263.625 MiB
Vertices found: 9843 and edges: 19683
Runtime = 0:29:03.321870
Mem usage at end: 296.8359375 MiB
sage: test(graphs.SierpinskiGasketGraph(10))
Mem usage at start: 303.11328125 MiB
Vertices found: 29526 and edges: 59049
Runtime = 5:01:45.355463
Mem usage at end: 399.3984375 MiB
```
### :memo: Checklist
<!-- Put an `x` in all the boxes that apply. -->
- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [x] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [x] I have updated the documentation and checked the documentation
preview.
### :hourglass: Dependencies
<!-- List all open PRs that this PR logically depends on. For example,
-->
<!-- - sagemath#12345: short description why this is a dependency -->
<!-- - sagemath#34567: ... -->
URL: sagemath#38791
Reported by: David Coudert
Reviewer(s): Dima Pasechnik
vbraun
pushed a commit
to vbraun/sage
that referenced
this pull request
Nov 13, 2024
…r graphs
This PR implements a non recursive version of method `gomory_hu_tree`
for graphs. This fixes the max recursion depth error reported in
https://ask.sagemath.org/question/79577/graphs-gomory-hu-tree-memory-
blow-up-and-max-recursion-depth/. The memory consumption is seriously
reduced.
Without this PR:
```py
sage: def test(g):
....: from datetime import datetime
....: import psutil
....: start_time = datetime.now()
....: process = psutil.Process(os.getpid())
....: mem = process.memory_info()[0] / float(2 ** 20)
....: print("Mem usage at start:", mem, "MiB")
....: try:
....: print("Vertices found:", g.order(), "and edges:",
g.size())
....: T = g.gomory_hu_tree(algorithm="FF")
....: except Exception as error:
....: print("Error detected:", error)
....: finally:
....: end_time = datetime.now()
....: print("Runtime =", end_time - start_time)
....: mem = process.memory_info()[0] / float(2 ** 20)
....: print("Mem usage at end:", mem, "MiB")
....:
sage: test(graphs.SierpinskiGasketGraph(5))
Mem usage at start: 241.0234375 MiB
Vertices found: 123 and edges: 243
Runtime = 0:00:00.243477
Mem usage at end: 252.1171875 MiB
sage: test(graphs.SierpinskiGasketGraph(6))
Mem usage at start: 252.1171875 MiB
Vertices found: 366 and edges: 729
Runtime = 0:00:02.050924
Mem usage at end: 324.30078125 MiB
sage: test(graphs.SierpinskiGasketGraph(7))
Mem usage at start: 324.30078125 MiB
Vertices found: 1095 and edges: 2187
Runtime = 0:00:21.207451
Mem usage at end: 968.97265625 MiB
sage: test(graphs.SierpinskiGasketGraph(8))
Mem usage at start: 950.25390625 MiB
Vertices found: 3282 and edges: 6561
Error detected: maximum recursion depth exceeded
Runtime = 0:04:36.154550
Mem usage at end: 6767.39453125 MiB
```
With this PR
```py
sage: test(graphs.SierpinskiGasketGraph(5))
Mem usage at start: 246.0859375 MiB
Vertices found: 123 and edges: 243
Runtime = 0:00:00.219925
Mem usage at end: 246.7109375 MiB
sage: test(graphs.SierpinskiGasketGraph(6))
Mem usage at start: 247.0234375 MiB
Vertices found: 366 and edges: 729
Runtime = 0:00:01.900761
Mem usage at end: 248.2734375 MiB
sage: test(graphs.SierpinskiGasketGraph(7))
Mem usage at start: 248.5859375 MiB
Vertices found: 1095 and edges: 2187
Runtime = 0:00:18.535145
Mem usage at end: 252.4921875 MiB
sage: test(graphs.SierpinskiGasketGraph(8))
Mem usage at start: 253.1171875 MiB
Vertices found: 3282 and edges: 6561
Runtime = 0:02:57.325506
Mem usage at end: 265.15234375 MiB
sage: test(graphs.SierpinskiGasketGraph(9))
Mem usage at start: 263.625 MiB
Vertices found: 9843 and edges: 19683
Runtime = 0:29:03.321870
Mem usage at end: 296.8359375 MiB
sage: test(graphs.SierpinskiGasketGraph(10))
Mem usage at start: 303.11328125 MiB
Vertices found: 29526 and edges: 59049
Runtime = 5:01:45.355463
Mem usage at end: 399.3984375 MiB
```
### :memo: Checklist
<!-- Put an `x` in all the boxes that apply. -->
- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [x] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [x] I have updated the documentation and checked the documentation
preview.
### :hourglass: Dependencies
<!-- List all open PRs that this PR logically depends on. For example,
-->
<!-- - sagemath#12345: short description why this is a dependency -->
<!-- - sagemath#34567: ... -->
URL: sagemath#38791
Reported by: David Coudert
Reviewer(s): Dima Pasechnik
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This PR implements a non recursive version of method
gomory_hu_treefor graphs. This fixes the max recursion depth error reported in https://ask.sagemath.org/question/79577/graphs-gomory-hu-tree-memory-blow-up-and-max-recursion-depth/. The memory consumption is seriously reduced.Without this PR:
With this PR
📝 Checklist
⌛ Dependencies