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<td class="page-title-pattern-first-line " style="padding: 0; border-collapse: collapse; font-family: Arial, sans-serif; font-size: 14px; padding-top: 10px"> <a href="https://hibernate.atlassian.net/browse/HHH" style="color: #3b73af; text-decoration: none">Hibernate ORM</a> / <a href="https://hibernate.atlassian.net/browse/HHH-10924" style="color: #3b73af; text-decoration: none"><img src="cid:jira-generated-image-avatar-7ad95843-7616-4ca3-afb7-a2d28144868a" height="16" width="16" border="0" align="absmiddle" alt="Improvement" style="vertical-align: text-bottom"></a> <a href="https://hibernate.atlassian.net/browse/HHH-10924" style="color: #3b73af; text-decoration: none">HHH-10924</a> </td>
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<td style="vertical-align: top;; padding: 0; border-collapse: collapse; padding-right: 5px; font-size: 20px; line-height: 30px; mso-line-height-rule: exactly" class="page-title-pattern-header-container"> <span class="page-title-pattern-header" style="font-family: Arial, sans-serif; padding: 0; font-size: 20px; line-height: 30px; mso-text-raise: 2px; mso-line-height-rule: exactly; vertical-align: middle"> <a href="https://hibernate.atlassian.net/browse/HHH-10924" style="color: #3b73af; text-decoration: none">Replace ConcurrentServiceBinding by ConcurrentHashMap</a> </span> </td>
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<td class="has-icon" style="padding: 0; border-collapse: collapse; font: normal 14px/20px Arial, sans-serif; padding: 2px 0 2px 5px; vertical-align: top"> <img src="cid:jira-generated-image-avatar-7ad95843-7616-4ca3-afb7-a2d28144868a" height="16" width="16" border="0" align="absmiddle" alt="Improvement" style="vertical-align: text-bottom"> Improvement </td>
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<td style="padding: 0; border-collapse: collapse; font: normal 14px/20px Arial, sans-serif; padding: 2px 0 2px 5px; vertical-align: top"> 5.2.1 </td>
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<th style="color: #707070; font: normal 14px/20px Arial, sans-serif; text-align: left; vertical-align: top; padding: 2px 0">Created:</th>
<td style="padding: 0; border-collapse: collapse; font: normal 14px/20px Arial, sans-serif; padding: 2px 0 2px 5px; vertical-align: top"> 04/Jul/2016 12:41 PM </td>
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<td class="has-icon" style="padding: 0; border-collapse: collapse; font: normal 14px/20px Arial, sans-serif; padding: 2px 0 2px 5px; vertical-align: top"> <img src="cid:jira-generated-image-static-major-18fd0ab4-1c0e-4a12-81d9-8e0bbd45a880" height="16" width="16" border="0" align="absmiddle" alt="Major" style="vertical-align: text-bottom"> Major </td>
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<td style="padding: 0; border-collapse: collapse; font: normal 14px/20px Arial, sans-serif; padding: 2px 0 2px 5px; vertical-align: top"> <a class="user-hover" rel="golovnin" id="email_golovnin" href="https://hibernate.atlassian.net/secure/ViewProfile.jspa?name=golovnin" style="color:#6c797f;; color: #3b73af; text-decoration: none">Andrej Golovnin</a> </td>
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<td class="text-paragraph-pattern-container mobile-resize-text " style="padding: 0; border-collapse: collapse; padding: 0 0 10px"> <p style="margin-top:0;margin-bottom:10px;; margin: 10px 0 0; margin-top: 0">While looking through the source code of Hibernate I found the class ConcurrentServiceBinding. My first thought was: cool idea, maybe I can use something similar too. And the second thought was: is it really faster than IdentityHashMap or ConcurrentHashMap. To answer this question I have created <a href="https://github.com/golovnin/hibernate-orm-jmh/blob/5.2/src/main/java/org/hibernate/service/internal/ConcurrentServiceBindingBenchmark.java" class="external-link" rel="nofollow" style="color: #3b73af; text-decoration: none">small JMH tests</a>. Here are the results from the execution of this tests on Intel Core i7 2 GHz:</p>
<div class="preformatted panel" style="border-width: 1px;; border: 1px solid #cccccc; background: #f5f5f5; font-size: 12px; line-height: 1.333; font-family: monospace; border: 1px solid #cccccc; -moz-border-radius: 3px; border-radius: 3px; margin: 9px 0">
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<pre style="margin: 10px 0 0; margin-top: 0; max-height: 30em; overflow: auto; white-space: pre-wrap; word-wrap: normal; white-space: pre; word-break: normal; word-wrap: break-word; word-break: break-all; white-space: pre-wrap"># JMH 1.12 (released 78 days ago)
# VM version: JDK 1.8.0_92, VM 25.92-b14
# VM options: <none>
# Warmup: 10 iterations, 3 s each
# Measurement: 10 iterations, 3 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Average time, time/op
Benchmark Mode Cnt Score Error Units
ConcurrentServiceBindingBenchmark.baseConcurrentServiceBindingGetEventListenerRegistry avgt 100 11.197 ± 0.534 ns/op
ConcurrentServiceBindingBenchmark.baseConcurrentServiceBindingGetJdbcServices avgt 100 8.126 ± 1.197 ns/op
ConcurrentServiceBindingBenchmark.chmConcurrentServiceBindingGetEventListenerRegistry avgt 100 6.594 ± 0.023 ns/op
ConcurrentServiceBindingBenchmark.chmConcurrentServiceBindingGetJdbcServices avgt 100 6.589 ± 0.025 ns/op
ConcurrentServiceBindingBenchmark.ihmConcurrentServiceBindingGetEventListenerRegistry avgt 100 6.206 ± 0.005 ns/op
ConcurrentServiceBindingBenchmark.ihmConcurrentServiceBindingGetJdbcServices avgt 100 6.325 ± 0.108 ns/op
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</div> <p style="margin-top:0;margin-bottom:10px;; margin: 10px 0 0">Same as above but with 10 threads:</p>
<div class="preformatted panel" style="border-width: 1px;; border: 1px solid #cccccc; background: #f5f5f5; font-size: 12px; line-height: 1.333; font-family: monospace; border: 1px solid #cccccc; -moz-border-radius: 3px; border-radius: 3px; margin: 9px 0">
<div class="preformattedContent panelContent" style="padding: 9px 12px">
<pre style="margin: 10px 0 0; margin-top: 0; max-height: 30em; overflow: auto; white-space: pre-wrap; word-wrap: normal; white-space: pre; word-break: normal; word-wrap: break-word; word-break: break-all; white-space: pre-wrap"># Threads: 10 threads, will synchronize iterations
Benchmark Mode Cnt Score Error Units
ConcurrentServiceBindingBenchmark.baseConcurrentServiceBindingGetEventListenerRegistry avgt 100 27.125 ± 0.967 ns/op
ConcurrentServiceBindingBenchmark.baseConcurrentServiceBindingGetJdbcServices avgt 100 27.019 ± 2.590 ns/op
ConcurrentServiceBindingBenchmark.chmConcurrentServiceBindingGetEventListenerRegistry avgt 100 18.367 ± 0.507 ns/op
ConcurrentServiceBindingBenchmark.chmConcurrentServiceBindingGetJdbcServices avgt 100 17.919 ± 0.403 ns/op
ConcurrentServiceBindingBenchmark.ihmConcurrentServiceBindingGetEventListenerRegistry avgt 100 17.049 ± 0.315 ns/op
ConcurrentServiceBindingBenchmark.ihmConcurrentServiceBindingGetJdbcServices avgt 100 17.871 ± 0.520 ns/op
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</div> <p style="margin-top:0;margin-bottom:10px;; margin: 10px 0 0">baseConcurrentServiceBindingXXX uses the current implementation of ConcurrentServiceBinding in Hibernate. chmConcurrentServiceBindingXXX uses ConcurrentHashMap and ihmConcurrentServiceBinding uses IdentityHashMap.</p> <p style="margin-top:0;margin-bottom:10px;; margin: 10px 0 0">As you can see CHM based implementation is faster than the current implementation of ConcurrentServiceBinding. The IdentityHashMap based implementation is only slightly faster than the CHM based. Therefore I think it is not worth to maintain an extra class when CHM is good enough and suggest to replace ConcurrentServiceBinding by ConcurrentHashMap.</p> </td>
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